Display device, electronic apparatus, and method of fabricating the display device

ABSTRACT

It is an object of the invention to provide a technique to manufacture a display device with high image quality and high reliability at low cost with high yield. The invention has spacers over a pixel electrode layer in a pixel region and over an insulating layer functioning as a partition which covers the periphery of the pixel electrode layer. When forming a light emitting material over a pixel electrode layer, a mask for selective formation is supported by the spacers, thereby preventing the mask from contacting the pixel electrode layer due to a twist and deflection thereof. Accordingly, such damage as a crack by the mask does not occur in the pixel electrode layer. Thus, the pixel electrode layer does not have a defect in shapes, thereby a display device which performs a high resolution display with high reliability can be manufactured.

TECHNICAL FIELD

The present invention relates to a display device, an electronicapparatus, and a method of fabricating the display device.

BACKGROUND ART

In order to perform a full color display by a display device providedwith an electroluminescence (hereinafter also referred to as EL)element, a color light emitting element which emits color light is used.One of important factors for forming a color light emitting element isto form a light emitting material of each color in a fine pattern overan electrode.

For the aforementioned purpose, generally used is a method for forming afine pattern using a mask when forming a material using a vapordeposition method and the like.

However, there is a problem in that a defect occurs due to a precisionand a deflection of a mask used in vapor deposition which is caused bythe fineness of a pixel region in accordance with higher resolution andthe large size of a substrate in accordance with a larger area. Aresearch aimed at high precision of a vapor deposition mask and highreliability has been reported (for example, see Japanese PatentLaid-Open No. 2000-129419.

SUMMARY OF THE INVENTION

The invention provides a technique to manufacture a display devicehaving high resolution and high reliability with high yield withoutcomplicating steps and apparatus.

Means for Solving the Problem

The invention has spacers over a pixel electrode layer in a pixel regionand over an insulating layer which functions as a partition covering theperiphery of the pixel electrode layer. When forming a light emittingmaterial over the pixel electrode layer, a mask for selective formationis supported by the spacers, thereby preventing the mask from contactingthe pixel electrode layer due to a twist and deflection thereof.Accordingly, such damage as a crack by the mask does not occur in thepixel electrode layer. Thus, the pixel electrode layer does not have adefect in shapes, thereby a display device which performs a highresolution display with high reliability can be manufactured.

A display device to which the invention can be applied includes a lightemitting display device in which a thin film transistor (hereinafteralso referred to as a TFT) is connected to a light emitting elementincluding electrodes and a layer containing an organic substance whichemits light called electroluminescence or a mixture of organic andinorganic substances interposed therebetween.

One of the display devices of the invention has a first spacer over afirst electrode layer, an insulating layer (insulator) covering an endportion of the first electrode layer, a second spacer over theinsulating layer, an electroluminescent layer over the first electrodelayer and the first spacer, and a second electrode layer over theelectroluminescent layer.

One of the display devices of the invention has a first spacer over afirst electrode layer, an insulating layer (insulator) covering an endportion of the first electrode layer, a second spacer over theinsulating layer, an electroluminescent layer over the first electrodelayer and the first spacer, and a second electrode layer over theelectroluminescent layer, and the insulating layer and the first spacerare made of the same material.

One of the display devices of the invention has a first spacer over afirst electrode layer, an insulating layer (insulator) covering an endportion of the first electrode layer, a second spacer over theinsulating layer, an electroluminescent layer over the first electrodelayer and the first spacer, and a second electrode layer over theelectroluminescent layer, and the first spacer and the second spacer aremade of the same material.

According to the aforementioned structures, the first spacer and theinsulating layer may be separated as in FIGS. 25 and 30 or continuouslyconnected as in FIGS. 26 and 30. Similarly, the first spacer and thesecond spacer may be separated or continuously connected. When formingan electroluminescent layer over the first electrode layer whichfunctions as a pixel electrode layer, the first spacer and the secondspacer become spacers for a mask being used as well as function asspacers to prevent damage and deformation of a display device due toexternal pressure or shocks even after forming the electroluminescentlayer and sealing with a scaling substrate to complete the displaydevice.

One of the methods for manufacturing a display device of the inventioncomprises: forming a first electrode layer, forming an insulating layer(insulator) covering an end portion of the first electrode layer and afirst spacer over the first electrode layer, forming a second spacerover the insulating layer, forming an electroluminescent layer over thefirst electrode layer and the first spacer, and forming a secondelectrode layer over the electroluminescent layer.

One of the methods for manufacturing a display device of the inventioncomprises: forming a first electrode layer, forming an insulating layer(insulator) covering an end portion of the first electrode layer and afirst spacer over the first electrode layer, providing a mask in contactwith a second spacer, selectively forming an electroluminescent layerover the first electrode layer and the first spacer, and forming asecond electrode layer over the electroluminescent layer.

One of the methods for manufacturing a display device of the inventioncomprises: forming a first electrode layer, forming an insulating layer(insulator) covering an end portion of the first electrode layer,forming a first spacer over the first electrode layer and a secondspacer over the insulating layer, forming an electroluminescent layerover the first electrode layer and the first spacer, and forming asecond electrode layer over the electroluminescent layer.

One of the methods for manufacturing a display device of the inventioncomprises: forming a first electrode layer, forming an insulating layer(insulator) covering an end portion of the first electrode layer,forming an insulating film (insulating layer) over the first electrodelayer and the insulating layer, patterning the insulating film to form afirst spacer over the first electrode layer and a second spacer over theinsulating layer, forming an electroluminescent layer over the firstelectrode layer and the first spacer, and forming a second electrodelayer over the electroluminescent layer.

One of the methods for manufacturing a display device of the inventioncomprises: forming a first electrode layer, forming an insulating layer(insulator) covering an end portion of the first electrode layer forminga first spacer over the first electrode layer and a second spacer overthe insulating layer providing a mask in contact with the second space,selectively forming an electroluminescent layer over the first electrodelayer and the first spacer, and forming a second electrode layer overthe electroluminescent layer.

Effect of the Invention

When using the invention, a display device with high reliability can bemanufactured by simplified steps. Therefore, a display device with highresolution and high image quality can be manufactured at low cost withhigh yield.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 Diagrams illustrating a display device of the invention.

FIG. 2 Diagrams illustrating a method for manufacturing a display deviceof the invention.

FIG. 3 Diagrams illustrating a method for manufacturing a display deviceof the invention.

FIG. 4 Diagrams illustrating a method for manufacturing a display deviceof the invention.

FIG. 5 Diagrams illustrating a method for manufacturing a display deviceof the invention.

FIG. 6 Diagrams illustrating a method for manufacturing a display deviceof the invention.

FIG. 7 Diagrams illustrating a method for manufacturing a display deviceof the invention.

FIG. 8 A diagram illustrating a display device of the invention.

FIG. 9 A diagram illustrating a display device of the invention.

FIG. 10 Diagrams illustrating a display device of the invention.

FIG. 11 A diagram illustrating a display device of the invention.

FIG. 12A diagram illustrating a display device of the invention.

FIG. 13 Diagrams illustrating structures of a light emitting elementapplicable to the invention.

FIG. 14 An equivalent circuit diagram of an EL display deviceillustrated in FIG. 15.

FIG. 15 A top plan view illustrating a display device of the invention.

FIG. 16 Top plan views each illustrating a display device of theinvention.

FIG. 17 Top plan views each illustrating a display device of theinvention.

FIG. 18A top plan view of a display device of the invention.

FIG. 19A diagram illustrating a droplet injection method applicable tothe invention.

FIG. 20 Views each showing an electronic apparatus to which theinvention is applied.

FIG. 21 Diagrams showing an electronic apparatus to which the inventionis applied.

FIG. 22A view showing an electronic apparatus to which the invention isapplied.

FIG. 23 Views each showing an electronic apparatus to which theinvention is applied.

FIG. 24A diagram illustrating a display device of the invention.

FIG. 25A top plan view of a display device of the invention.

FIG. 26A top plan view of a display device of the invention.

FIG. 27 Top plan views each illustrating a display device of theinvention.

FIG. 28 Diagrams each illustrating a display device of the invention.

FIG. 29 Diagrams illustrating a method for manufacturing a displaydevice of the invention.

FIG. 30A top plan view of a display device of the invention.

FIG. 31 Diagrams each illustrating a display device of the invention.

FIG. 32A diagram illustrating a method for manufacturing a displaydevice of the invention.

FIG. 33A top plan view of a display device of the invention.

FIG. 34 Top plan views each of a display device of the invention.

FIG. 35 A diagram illustrating a display device of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiment modes of the invention are described in detail with referenceto drawings. However, the invention is not limited to the followingdescription and those skilled in the art easily understand that themodes and details can be varied, unless such changes and modificationsdepart from the theme and scope of the invention. Therefore, theinvention is not construed limited in the description of the embodimentmodes described below. Note that in the structure of the invention whichis described below, the same reference numerals are used in common foridentical portions or portions having a similar function in differentdrawings and repetitive descriptions thereof are omitted.

Embodiment Mode 1

A method for manufacturing a thin film transistor of this embodimentmode is described in details with reference to FIGS. 1 to 6, 16 and 17.

FIG. 16(A) is a top plan view showing a structure of a display panel inaccordance with the invention, in which a pixel portion 2701 wherepixels 2702 are arranged in matrix, a scan line side input terminal2703, and a signal line side input terminal 2704 are formed over asubstrate 2700 having an insulating surface. The number of pixels may beset in accordance with various standards, and 1024×768×3 (RGB) pixelsmay be provided in the case of XGA, 1600×1200×3 (RGB) pixels may beprovided in the case of UXGA, and 1920×1080×3 (RGB) pixels may beprovided in the case of corresponding to a full spec high vision.

Scan lines extending from the scan line side input terminal 2703 andsignal lines extending from the signal line side input terminal 2704cross each other so that the pixels 2702 are disposed in matrix. Eachpixel 2702 is provided with a switching element and a pixel electrodelayer connected thereto. A typical example of the switching element is aTFT. A gate electrode layer side of the TFT is connected to the scanline, and a source or drain side thereof is connected to the signalline, thereby each pixel can be controlled independently by a signalinputted externally.

A semiconductor layer, a gate insulating layer and a gate electrodelayer are major components of a TFT. A wiring layer connected to sourceand drain regions formed in the semiconductor layer is attached thereto.Typically known structures are a top gate type in which a semiconductorlayer, a gate insulating layer, and a gate electrode layer are disposedfrom a substrate side, a bottom gate type in which a gate electrodelayer, a gate insulating layer, and a semiconductor layer are disposedfrom a substrate side and the like, and any of the aforementionedstructures may be used for the invention.

FIG. 16(A) shows a structure of a display panel in which signalsinputted to the scan line and the signal line are controlled by anexternal driver circuit, however, a driver IC 2751 may be mounted on thesubstrate 2700 by a COG (Chip on Glass) method as shown in FIG. 17(A).Further, as another mode of mounting, a TAB (Tape Automated Bonding)method as shown in FIG. 17(B) may be used as well. A driver IC may beformed using a single crystalline semiconductor substrate or using acircuit formed with TFTs over a glass substrate. In FIG. 17, the driverIC 2751 is connected to an FPC (Flexible printed circuit) 2750.

Further, in the case of forming a TFT provided in a pixel using asemiconductor having crystallinity, a scan line side driver circuit 3702can be formed over a substrate 3700 to be integrated as shown in FIG.16(B). In FIG. 16(B), a pixel portion 3701 is controlled by an externaldriver circuit connected to a signal line side input terminal 3704similarly to FIG. 16(A). In the case where a TFT provided in a pixel isformed using a polycrystalline (microcrystalline) semiconductor, asingle crystalline semiconductor and the like with high mobility, apixel portion 4701, a scan line driver circuit 4702, and a signal linedriver circuit 4704 can be integrally formed over a substrate 4700 inFIG. 16(C).

As a base film over a substrate 100 having an insulating surface, asilicon nitride oxide film (SiNO) is used to form a base film 101 a witha thickness of 10 to 200 nm (preferably 50 to 100 nm) and a siliconoxynitride film (SiON) is used to stack a base film 101 b with athickness of 50 to 200 nm (preferably 100 to 150 nm) by a sputteringmethod, a CVD method (Physical Vapor Deposition), a CVD method (ChemicalVapor Deposition) such as a low pressure CVD method (LPCVD method), or aplasma CVD method and the like. In this embodiment mode, the base film101 a and the base film 101 b are formed using a plasma CVD method. Asthe substrate 100, a glass substrate, a quartz substrate, a siliconsubstrate, a metal substrate, or a stainless substrate each having asurface covered with an insulating film may be used. Further, a plasticsubstrate having heat resistance which can resist a processingtemperature of this embodiment mode may be used or a flexible substratesuch as a film may be used as well. As a plastic substrate, a substrateformed of PET (polyethylene terephthalate), PEN (polyethylenenaphthalate), or PES (polyether sulfone) can be used while a syntheticresin such as acrylic may be used as a flexible substrate.

As a base film, silicon oxide, silicon nitride, silicon oxynitride,silicon nitride oxide and the like can be used, and a single layer or astacked structure such as two layers or three layers may be as well.Note that in this specification, silicon oxynitride is a substance inwhich a composition ratio of oxygen is higher than a composition ratioof nitrogen and can also be referred to as silicon oxide containingnitrogen. Similarly, silicon nitride oxide is a substance in which acomposition ratio of nitrogen is higher than a composition ratio ofoxygen and can also be referred to as silicon nitride containing oxygen.In this embodiment mode, a silicon nitride oxide film is formed over thesubstrate with a thickness of 50 nm using SiH₄, NH₃, N₂O, N₂, and H₂ asa reaction gas, and a silicon oxynitride film is formed thereover with athickness of 100 nm using SiH₄ and N₂O as a reaction gas. Alternatively,the silicon nitride oxide film may be formed with a thickness of 140 nmand the silicon oxynitride film to be stacked may be formed with athickness of 100 nm.

It is preferable to form a silicon nitride film or a silicon nitrideoxide film with a thickness of 0.3 to 5 nm as a top layer of the basefilm in contact with the semiconductor layer. In this embodiment mode, ametal element (in this embodiment mode, nickel is used) for promotingcrystallization is added to the semiconductor layer and thereafterremoved by performing gettering process. Although an interface conditionbetween a silicon oxide film and a silicon film is favorable, there maybe a case where a metal element in the silicon film and oxygen insilicon oxide react in the interface to easily become a metal oxide (inthis embodiment mode, nickel oxide (NiO_(x))), thereby the metal elementis not easily gettered. Moreover, it is concerned a silicon nitride filmmay adversely affect the interface condition with the semiconductorlayer due to a stress of the silicon nitride film and an effect of atrap. Therefore, a silicon nitride film or a silicon nitride oxide filmis formed with a thickness of 0.3 to 5 nm as a top layer of aninsulating layer in contact with the semiconductor layer. In thisembodiment mode, after stacking a silicon nitride oxide film and asilicon oxynitride film over the substrate 100, a silicon nitride oxidefilm is formed with a thickness of 0.3 nm to 5 nm over the siliconoxynitride film to form a stacked structure of three layers. With such astructure, a gettering efficiency of a metal element in thesemiconductor layer increases and the adverse effect of the siliconnitride film on the semiconductor layer can be reduced. Further, theinsulating layer to be stacked is preferably formed continuously bychanging a reaction gas at the same temperature without breaking thevacuum in the same chamber. By continuously forming without breaking thevacuum, an interface between the stacked films can be prevented fromcontamination.

Subsequently, a semiconductor film is formed over the base film. Thesemiconductor film may be formed by a known means (a sputtering method,an LPCVD method, a plasma CVD method or the like) with a thickness of 25to 200 nm (preferably 30 to 150 nm). In this embodiment mode, it ispreferable to use a crystalline semiconductor film formed by lasercrystallizing an amorphous semiconductor film.

A material for forming the semiconductor film includes an amorphoussemiconductor (hereinafter also referred to as “amorphous semiconductor:AS”) manufactured by a vapor deposition method or a sputtering methodusing a semiconductor material gas typified by silane and germane, apolycrystalline semiconductor which is obtained by crystalling anamorphous semiconductor using light energy or heat energy, asemi-amorphous (also referred to as microcrystal or fine crystal.Hereinafter also referred to as “SAS”) semiconductor and the like.

The SAS is a semiconductor having an intermediate structure betweenamorphous and crystalline (including single crystalline andpolycrystalline) structures and having a third state which is stable infree energy. Moreover, the SAS includes a crystalline region having ashort range order and lattice distortion, and at least in a portion of aregion in the film, a crystalline region of 0.5 to 20 nm can beobserved. In the case of containing silicon as a main component, Ramanspectrum is shifted toward a lower wavenumber than 520 cm⁻¹. Diffractionpeaks of (111) and (220), which are believed to be derived from siliconcrystal lattice, are observed by X-ray diffraction. Hydrogen or halogenis contained at least by 1 atom % or more for terminating dangling bonds(dangling bonds). The SAS is formed by decomposing a silicon source gasthrough glow discharge (plasma CVD). As the silicon source gas, SiH₄, aswell as Si₂H₆, SiH₂Cl₂, SiHCl₃, SiCl₄, SiF₄ and the like can be used.Further, F₂ and GeF₄ may be mixed as well. The silicon source gas may bediluted with H₂ or a mixed gas of H₂ and one or more of rare gaselements selected from He, Ar, Kr, and Ne. A dilution ratio is set in arange of 2 to 1000 times, pressure is set in a range of approximately0.1 Pa to 133 Pa, and a power supply frequency is set to 1 MHz to 120MHz, preferably 13 MHz to 60 MHz. It is preferable that a temperaturefor heating the substrate be 300° C. or lower, but a temperature forheating the substrate may be 100 to 200° C. as well. Here, it ispreferable that impurities derived from atmospheric components such asoxygen, nitrogen, and carbon as impurity elements which are introducedmainly at the film deposition be 1×10²⁰ cm⁻³ or less. In particular,oxygen concentration is preferably 5×10¹⁹/cm⁻³ or less and morepreferably 1×10¹⁹/cm⁻³ or less. Further, when a rare gas element such ashelium, argon, krypton, or neon is included so that the latticedistortion is increased further and the stability is thus enhanced, afavorable SAS can be obtained. Moreover, as the semiconductor film, anSAS layer formed with a silicon source gas containing hydrogen may bestacked over an SAS layer formed with a silicon source gas containingfluorine.

As a typical amorphous semiconductor, there are hydrogenated amorphoussilicon while as a typical crystalline semiconductor, there arepolysilicon and the like. Polysilicon (polycrystalline silicon) includeswhat is called high temperature polysilicon using polysilicon as a mainmaterial which is formed at a processing temperature of 800° C. orhigher, what is called low temperature polysilicon using polysilicon asa main material which is formed at a processing temperature of 600° C.or lower, polysilicon crystallized by adding an element which promotescrystallization and the like. It is needless to say that asemi-amorphous semiconductor or a semiconductor containing a crystalphase in a portion of a semiconductor film can be used as describedabove.

In the case of using a crystalline semiconductor film for thesemiconductor film, a known method (a laser crystallization method, athermal crystallization method, a thermal crystallization method usingan element such as nickel which promotes crystallization and the like)may be used for a method for manufacturing the crystalline semiconductorfilm. Further, a microcrystalline semiconductor as an SAS may becrystallized by laser irradiation so that crystallinity thereof can beenhanced. In the case where an element which promotes crystallization isnot introduced, the amorphous semiconductor film is heated at 500° C.for 1 hour in a nitrogen atmosphere to discharge hydrogen so that ahydrogen concentration of the amorphous semiconductor film is 1×10²⁰atoms/cm³ or lower before irradiating the amorphous semiconductor filmwith laser light. This is because if the amorphous semiconductor filmcontaining a lot of hydrogen is irradiated with laser light, theamorphous semiconductor film may be broken. An annealing furnace, laserirradiation, irradiation of light emitted from a lamp (also referred toas lamp annealing) or the like can be used for the heat treatment forcrystallization. As a heating method, there are RTA methods such as aGRTA (Gas Rapid Thermal Anneal) method and an LRTA (Lamp Rapid ThermalAnneal) method.

A method for introducing a metal element into the amorphoussemiconductor film is not particularly limited as long as it is a methodfor making the metal element exist over a surface of the amorphoussemiconductor film or inside thereof. For example, a sputtering method,a CVD method, a plasma treatment method (including a plasma CVD method),an adsorption method, or a method of applying a solution of metal saltcan be used. Among these, a method of using a solution is easy andadvantageous in that the concentration of the metal element can beeasily controlled. Moreover, at this time, it is desirable to form anoxide film by UV light irradiation in an oxygen atmosphere, a thermaloxidation method, treatment with ozone water containing hydroxyl radicalor hydrogen peroxide, or the like to improve wettability of a surface ofthe amorphous semiconductor film to diffuse an aqueous solution over theentire surface of the amorphous semiconductor film.

By irradiation of a second harmonic to fourth harmonic laser light of afundamental wave using a solid state laser capable of continuousoscillation, large grain crystals can be obtained. Typically, forexample, it is desirable to use a second harmonic (532 nm) and thirdharmonic (355 nm) of an Nd:YVO₄ laser (fundamental wave is 1064 nm).Specifically, laser light emitted from the continuous oscillation YVO₄laser is converted into a harmonic by a non-linear optical element,thereby laser light having an output of several W or higher is obtained.It is preferable to form laser light into a rectangular or ellipticalshape on an irradiated surface by an optical system to irradiate asemiconductor film. An energy density at this time is required to beabout 0.001 to 100 MW/cm² (preferably 0.1 to 10 MW/cm²). Then, thesemiconductor film is irradiated at a scan rate of about 0.5 to 2000cm/sec (preferably 10 to 200 cm/sec).

It is preferable that a shape of a laser beam be linear. As a result,throughput can be improved. Furthermore, a semiconductor film ispreferably irradiated with laser at an incident angle θ (0<θ<90°),thereby an interference of the laser can be prevented.

Such laser and the semiconductor film are relatively scanned, therebylaser irradiation can be performed. Further, in the laser irradiation, amarker can be formed for overlapping beams at high precision andcontrolling a position to start laser irradiation and a position tofinish laser irradiation. The marker may be formed over the substrate atthe same time as the amorphous semiconductor film.

Note that a gas laser, a solid state laser, a copper vapor laser, a goldvapor laser and the like of continuous oscillation or pulsed oscillationcan be used as a laser. As examples of a gas laser, there are an excimerlaser, an Ar laser, a Kr laser, an He—Cd laser and the like while asexamples of a solid state laser, there are a YAG laser, a YVO₄ laser, aYLF laser, a YAlO₃ laser, a Y₂O₃ laser, a glass laser, a ruby laser, analexandrite laser, a Ti:sapphire laser and the like.

Moreover, the laser crystallization may be performed using laser lightof pulsed oscillation at a repetition rate of 0.5 MHz or higher, whichis a drastically higher range of repetition rates than a generally usedrange of repetition rates of several ten Hz to several hundred Hz. It issaid that it takes several ten to several hundred nsec for asemiconductor film to be completely solidified after it is irradiatedwith laser light of a pulsed oscillation. Therefore, by using theaforementioned range of repetition rate the semiconductor film can beirradiated with the following pulse of the laser light after thesemiconductor film is melted by the laser light until it is solidified.Accordingly, solid-liquid interface can be continuously moved in thesemiconductor film, therefore, a semiconductor film having crystalgrains that grow continuously in a scanning direction is formed.Specifically, an aggregate of contained crystal grains having widths of10 to 30 μm in the scanning direction and widths of about 1 to 5 μm in adirection perpendicular to the scanning direction can be formed. Byforming crystal grains of single crystal that extend long along thescanning direction, a semiconductor film which has almost no grainboundary at least in a channel direction of a thin film transistor canbe formed.

Further, irradiation of laser light may be performed in an inert gasatmosphere such as rare gas or nitrogen. Therefore, roughness of asurface of the semiconductor film due to laser light irradiation can besuppressed, and variation of a threshold due to variation of interfacestate densities can be suppressed.

An amorphous semiconductor film may be crystallized by the combinationof thermal treatment and laser light irradiation, or one of thermaltreatment and laser light irradiation may be performed a plurality oftimes.

In this embodiment mode, an amorphous semiconductor film is formed overthe base film 101 b and the amorphous semiconductor film is crystallizedto form a crystalline semiconductor film. As the amorphous semiconductorfilm, amorphous silicon formed using a reaction gas of SiH₄ and H₂ isused. In this embodiment mode, the base film 101 a, the base film 101 b,and the amorphous semiconductor film are continuously formed by changinga reaction gas without breaking the vacuum in the same chamber at thesame temperature of 330° C.

After removing an oxide film formed over the amorphous semiconductorfilm, an oxide film is formed with a thickness of 10 to 50 Å by UV lightirradiation in an oxygen atmosphere, a thermal oxidization method,treatment with ozone water containing hydroxy radical or hydrogenperoxide, or the like. In this embodiment mode, Ni is used as an elementfor promoting crystallization. An aqueous solution containing 10 ppm ofNi acetate is applied by a spin coating method.

In this embodiment mode, after performing thermal treatment at 650° for6 minutes by an RTA method, the oxide film formed over the semiconductorfilm is removed and laser light irradiation is performed. The amorphoussemiconductor film is crystallized by the aforementioned crystallizationtreatment to form a crystalline semiconductor film.

In the case of performing crystallization using a metal element, agettering step is performed for reducing or removing the metal element.In this embodiment mode, the metal element is captured using theamorphous semiconductor film as a gettering sink. First, an oxide filmis formed over the crystalline semiconductor film by UV lightirradiation in an oxygen atmosphere, a thermal oxidation method,treatment with ozone water containing hydroxyl radical or hydrogenperoxide, or the like. It is desirable that the oxide film be formedthicker by heat treatment. In this embodiment mode, after forming theoxide film, the oxide film is formed thicker by performing thermaltreatment at 650° C. for 6 minutes by an RTA method. Subsequently, anamorphous semiconductor film is formed with a thickness of 30 nm by aplasma CVD method (with a condition of this embodiment mode as 350 W and35 Pa).

After that, thermal treatment is performed at 650° C. for 6 minutes byan RTA method to reduce or remove the metal element. The thermaltreatment may be performed in a nitrogen atmosphere. Then, the amorphoussemiconductor film as a gettering sink and an oxide film formed over theamorphous semiconductor film are removed with hydrofluoric acid and thelike, thereby a crystalline semiconductor film 102 in which the metalelement is reduced or removed can be obtained (see FIG. 2(A)). In thisembodiment mode, the amorphous semiconductor film as a gettering sink isremoved using TMAH (Tetramethyl ammonium hydroxide).

The semiconductor film obtained in this manner may be doped with aslight amount of impurity elements (boron or phosphorus) for controllinga threshold voltage of a thin film transistor. This doping of impurityelements may be performed to an amorphous semiconductor film before acrystallization step. When impurity elements are doped in a state of theamorphous semiconductor film, the impurities can be activated by heattreatment for crystallization later. Further, a defect and the likegenerated at the doping can be improved as well.

Subsequently, the crystalline semiconductor film 102 is patterned usinga mask. In this embodiment mode, after removing the oxide film formedover the crystalline semiconductor film 102, an oxide film is newlyformed. Then, a photo mask is manufactured and a patterning process isapplied using a photolithography method, thereby a semiconductor layer103, a semiconductor layer 104, a semiconductor layer 105, and asemiconductor layer 106 are formed.

An etching process at the patterning may adopt either plasma etching(dry etching) or wet etching. However, in the case of processing a largearea substrate, plasma etching is suitable. As an etching gas, a gascontaining fluorine such as CF₄ and NF₃ or a gas containing chlorinesuch as Cl₂ and BCl₃ is used, to which an inert gas such as He and Armay be appropriately added. Further, in the case of applying an etchingprocess by atmospheric pressure discharge, local discharge processingcan be realized, thereby a mask layer is not required to be formed overan entire surface of the substrate.

In the invention, a conductive layer for forming a wiring layer or anelectrode layer, a mask layer for forming a predetermined pattern, orthe like may be formed by a method where a pattern can be selectivelyformed such as a droplet discharge method. In the droplet discharge(ejecting) method (also referred to as an inkjet method depending on thesystem thereof), a predetermined pattern (a conductive layer, aninsulating layer, and the like) can be formed by selectively discharging(ejecting) a droplet of a composition prepared for a specific purpose.At this time, a process for controlling wettability and adhesion may beperformed to a region for forming a pattern. Additionally, a method fortransferring or describing a pattern, for example, a printing method (amethod for forming a pattern such as screen printing and offsetprinting) or the like can be used.

In this embodiment mode, a resin material such as an epoxy resin, anacrylic resin, a phenol resin, a novolac resin, a melamine resin, or aurethane resin is used for a mask to be used. Alternatively, the maskmay be formed using an organic material such as benzocyclobutene,parylene, and polyimide having a transmitting property; a compoundmaterial formed by polymerization of siloxane polymers or the like; acomposition material containing a water-soluble homopolymer and awater-soluble copolymer; and the like. In addition, a commerciallyavailable resist material containing a photosensitive agent may also beused. For example, a novolac resin and a naphthoquinonediazide compoundthat are a photosensitive agent, which are typical positive type resist;a base resin, diphenylsilanediol, an acid generating material that are anegative type resist, and the like may be used. In the case where adroplet discharge method is used, even when any material is used, thesurface tension and the viscosity are appropriately adjusted bycontrolling the solvent concentration, adding a surfactant, or the like.

The oxide film over the semiconductor layer is removed to form a gateinsulating layer 107 covering the semiconductor layer 103, thesemiconductor layer 104, the semiconductor layer 105, and thesemiconductor layer 106. The gate insulating layer 107 is formed of aninsulating film containing silicon with a thickness of 10 to 150 nmusing a plasma CVD method or a sputtering method. The gate insulatinglayer 107 may be formed of a known material such as an oxide material ornitride material of silicon, typified by silicon nitride, silicon oxide,silicon oxynitride, and silicon nitride oxide and may be stacked layersor a single layer. In this embodiment mode, three stacked layers of asilicon nitride film, a silicon oxide film, and a silicon nitride filmare used for the gate insulating layer. Alternatively, a single layer ofa silicon oxynitride film or stacked layers of two layers of the siliconoxynitride film and one of the aforementioned films may be employed aswell. Preferably, a silicon nitride film with a dense film quality maybe used. Furthermore, a thin silicon oxide film may be formed betweenthe semiconductor layer and the gate insulating layer with a thicknessof 1 to 100 nm, preferably 1 to 10 nm, and more preferably 2 to 5 nm. Asa method for forming the thin silicon oxide film, the surface of thesemiconductor region is oxidized by a GRTA method, an LRTA method, orthe like to form a thermal oxide film is formed, thereby a silicon oxidefilm with a thin thickness can be formed. Note that a rare gas elementsuch as argon may be contained in a reaction gas so as to be mixed intoan insulating film to be formed in order to form a dense insulating filmhaving a little gate leak current at low film deposition temperature.

Subsequently, a first conductive film 108 with a thickness of 20 to 100nm and a second conductive film 109 with a thickness of 100 to 400 nm,each of which is used as a gate electrode layer are stacked over thegate insulating layer 107 (see FIG. 2(B)). The first conductive film 108and the second conductive film 109 can be formed by a known method suchas a sputtering method, a vapor deposition method, or a CVD method. Thefirst conductive film 108 and the second conductive film 109 may beformed of an element selected from tantalum (Ta), tungsten (W), titanium(Ti), molybdenum (Mo), aluminum (Al), copper (Cu), chromium (Cr), andneodymium (Nd), or an alloy material or compound material having theaforementioned element as a main component. Moreover, a semiconductorfilm typified by a polycrystalline silicon film which is doped withimpurity elements such as phosphorus or an AgPdCu alloy may be used asthe first conductive film 108 and the second conductive film 109.Further, the gate electrode layer is not limited to the two-layerstructure, and for example, may have a three-layer structure in which atungsten film with a thickness of 50 nm as the first conductive film, analloy film of aluminum and silicon (Al—Si) with a thickness of 500 nm asthe second conductive film, and a titanium nitride film with a thicknessof 30 nm as the third conductive film are sequentially stacked.Moreover, in the case of the three-layer structure, tungsten nitride maybe used instead of tungsten as the first conductive film; an alloy filmof aluminum and titanium (Al—Ti) may be used instead of the alloy filmof aluminum and silicon (Al—Si) as the second conductive film; or atitanium film may be used instead of the titanium nitride film as thethird conductive film. Further, a single-layer structure may also beused. In this embodiment mode, tantalum nitride (TaN) is formed with athickness of 30 nm as the first conductive film 108 and tungsten (W) isformed with a thickness of 370 nm as the second conductive film 109.

Subsequently, formed are a mask 110 a, a mask 110 b, a mask 110 c, amask 110 d, and a mask 110 f each of which is formed with a resist usinga photolithography method and the first conductive film 108 and thesecond conductive film 108 are patterned to form a first gate electrodelayer 121, a first gate electrode layer 122, a conductive layer 123, afirst gate electrode layer 124, a first gate electrode layer 125, afirst gate electrode layer 126, a conductive layer 111, a conductivelayer 112, a conductive layer 113, a conductive layer 114, a conductivelayer 115, and a conductive layer 116 (see FIG. 2(C)). The first gateelectrode layer 121, the first gate electrode layer 122, the conductivelayer 123, the first gate electrode layer 124, the first gate electrodelayer 125, the first gate electrode layer 126, the conductive layer 111,the conductive layer 112, the conductive layer 113, the conductive layer114, the conductive layer 115, and the conductive layer 116 can beetched to have a desired tapered shape by appropriately adjustingetching conditions (amount of power applied to a coiled electrode layer,amount of power applied to an electrode layer on a substrate side,electrode temperature on a substrate side, or the like) using an ICP(Inductively Coupled Plasma: inductively coupled plasma) etching method.Further, an angle and the like of the tapered shape can be controlled bythe shapes of the mask 110 a, the mask 110 b, the mask 110 c, the mask110 d, and the mask 110 f. Note that as an etching gas, a chlorine-basedgas typified by Cl₂, BCl₃, SiCl₄, CCl₄, or the like, a fluorine-basedgas typified by CF₄, CF₅, SF₆, NF₃, or the like, or O₂ can beappropriately used. In this embodiment mode, the second conductive film109 is etched using an etching gas containing CF₅, Cl₂, and O₂ and thenthe first conductive film 108 is continuously etched using an etchinggas containing CF₅ and Cl₂.

Subsequently, the conductive layer 111, the conductive layer 112, theconductive layer 113, the conductive layer 114, the conductive layer115, and the conductive layer 116 are patterned using the mask 110 a,the mask 110 b, the mask 110 c, the mask 110 d, and the mask 110 f. Atthis time, the conductive layers are etched with an etching condition ofhigh selection ratio between the second conductive film 109 which formsthe conductive layers and the first conductive film 108 which forms thefirst gate electrode layers. By this etching, the conductive layer 111,the conductive layer 112, the conductive layer 113, the conductive layer114, the conductive layer 115, and the conductive layer 116 are etchedto form a second gate electrode layer 131, a second gate electrode layer132, a conductive layer 133, a second gate electrode layer 134, a secondgate electrode layer 135, and a second gate electrode layer 136. In thisembodiment mode, although a third conductive layer also has a taperedshape, the tapered angle thereof is larger than the tapered angle of thefirst gate electrode layer 121, the first gate electrode layer 122, theconductive layer 123, the first gate electrode layer 124, the first gateelectrode layer 125, and the first gate electrode layer 126. Note thatthe tapered angle is a side angle to the surfaces of the first gateelectrode layer, the second gate electrode layer, and the conductivelayer. Accordingly, in the case where the tapered angle is increased to90°, the conductive layer has a perpendicular side and no tapered shape.In this embodiment mode, Cl₂, SF₆, and O₂ are used as an etching gas toform the second gate electrode layers.

In this embodiment mode, each of the first gate electrode layer, theconductive layer, and the second gate electrode layer is formed to havea tapered shape, therefore, both of the two gate electrode layers havetapered shapes. However, the invention is not limited to this and one ofthe gate electrode layers may have a tapered shape while the otherthereof may have a perpendicular side by anisotropic etching. As in thisembodiment mode, the tapered angles may be different or the same betweenthe stacked gate electrode layers. With a tapered shape, coverage of afilm to be stacked thereover is improved and defects are reduced toimprove reliability.

By the aforementioned steps, a gate electrode layer 117 formed of thefirst gate electrode layer 121 and the second gate electrode layer 131,and a gate electrode layer 118 formed of the first gate electrode layer122 and the second gate electrode layer 132 can be formed in aperipheral driver circuit region 204; a gate electrode layer 127 formedof the first gate electrode layer 124 and the second gate electrodelayer 134, a gate electrode layer 128 formed of the first gate electrodelayer 125 and the second gate electrode layer 135, a gate electrodelayer 129 formed of the first gate electrode layer 126 and the secondgate electrode layer 136 can be formed in a pixel region 206; and aconductive layer 130 formed of the conductive layer 123 and theconductive layer 133 can be formed in a connecting region 205 (see FIG.2(D)). In this embodiment mode, the gate electrode layers are formed bydry etching, however, wet etching may be employed as well.

The gate insulating layer 107 may be etched to some extent and reducedin thickness (what is called film thickness reduction) by an etchingstep when forming the gate electrode layers.

When forming the gate electrode layer, by thinning a width of the gateelectrode layer, a thin film transistor capable of high speed operationcan be formed. Two methods by which a width of the gate electrode layerin a channel direction is formed thin are described as follows.

A first method is to form a mask for a gate electrode layer, and then,slim the mask in a width direction by etching, ashing and the like toform a mask with a thinner width. By using a mask which is formed inadvance to have a shape with a thinner width, the gate electrode layercan be formed in a shape with a thinner width as well.

Subsequently, a second method is to form a normal mask to form a gateelectrode layer using the mask. Then, the obtained gate electrode layeris side-etched in a width direction to be thinned. Accordingly, a gateelectrode layer with a thinner width can be formed finally. Through theaforementioned steps, a thin film transistor with a short channel lengthcan be formed later so that a thin film transistor capable of high speedoperation can be formed.

Subsequently, an impurity element 151 which imparts n type is added withthe gate electrode layer 117, the gate electrode layer 118, the gateelectrode layer 127, the gate electrode layer 128, the gate electrodelayer 129, and the conductive layer 130 as masks to form a first n-typeimpurity region 140 a, a first n-type impurity region 140 b, a firstn-type impurity region 141 a, a first n-type impurity region 141 b, afirst n-type impurity region 142 a, a first n-type impurity region 142b, a first n-type impurity region 142 c, a first n-type impurity region143 a, and a first n-type impurity region 143 b (see FIG. 3(A)). In thisembodiment mode, doping is performed using phosphine (PH₃) (thecomposition rate of P is 5%) as a doping gas containing an impurityelement at a gas flow rate of 80 sccm, a beam current of 54 μA/cm, anacceleration voltage of 50 kV, and an adding dosage of 7.0×10¹³ions/cm². Here, doping is performed so that the impurity element whichimparts n type is contained at a concentration of about 1×10¹⁷ to5×10¹⁸/cm³ in the first n-type impurity region 140 a, the first n-typeimpurity region 1406, the first n-type impurity region 141 a, the firstn-type impurity region 141 b, the first n-type impurity region 142 a,the first n-type impurity region 142 b, the first n-type impurity region142 c, the first n-type impurity region 143 a, and the first n-typeimpurity region 143 b. In this embodiment mode, phosphorus (P) is usedas the impurity element which imparts n type.

In this embodiment mode, regions of the impurity regions which overlapthe gate electrode layers with the gate insulating layer interposedtherebetween are denoted as Lov regions, while regions of the impurityregions which do not overlap the gate electrode layers with the gateinsulating layer interposed therebetween are denoted as Loff regions. InFIG. 3A, the impurity regions are shown by hatching and blank spaces.However, this does not mean that impurity elements are not added to theblank spaces, but is for understanding intuitively that theconcentration distribution of the impurity element in this regionreflects the mask and the doping condition. Note that this is similar toother drawings of this specification.

Subsequently, a mask 153 a, a mask 153 b, a mask 153 c, and a mask 153 dwhich cover the semiconductor layer 103, a portion of the semiconductorlayer 105 and the semiconductor layer 106 are formed. Using the mask 153a, the mask 153 b, the mask 153 c, the mask 153 d, and the second gateelectrode layer 132 as masks, an impurity element 152 which imparts ntype is added to form a second n-type impurity region 144 a, a secondn-type impurity region 144 b, a third n-type impurity region 145 a, athird n-type impurity region 145 b, a second n-type impurity region 147a, a second n-type impurity region 1476, a second n-type impurity region147 c, a third n-type impurity region 148 a, a third n-type impurityregion 148 b, a third n-type impurity region 148 c, and a third n-typeimpurity region 148 d. In this embodiment mode, doping is performedusing PH₃ (the composition rate of P is 5%) as a doping gas containingan impurity element at a gas flow rate of 80 sccm, a beam current of 540μA/cm, an acceleration voltage of 70 kV, and an adding dosage of5.0×10¹⁵ ions/cm². Here, doping is performed so that the impurityelement which imparts n type is contained at a concentration of about5×10¹⁹ to 5×10²⁰/cm³ in the second n-type impurity region 144 a and thesecond n-type impurity region 144 b. The third n-type impurity region145 a and the third n-type impurity region 145 b are formed to containthe impurity element which imparts n type at an approximately the sameconcentration as or a slightly higher concentration than the thirdn-type impurity region 148 a, the third n-type impurity region 148 b,the third n-type impurity region 148 c, and the third n-type impurityregion 148 d. Further, a channel forming region 146 is formed in thesemiconductor layer 104, and a channel forming region 149 a and achannel forming region 149 b are formed in the semiconductor layer 105.

The second n-type impurity region 144 a, the second n-type impurityregion 144 b, the second n-type impurity region 147 a, the second n-typeimpurity region 147 b, and the second n-type impurity region 147 c arehigh concentration n-type impurity regions which function as sources ordrains. On the other hand, the third n-type impurity region 145 a, thethird n-type impurity region 145 b, the third n-type impurity region 148a, the third n-type impurity region 148 b, the third n-type impurityregion 148 c, and the third n-type impurity region 148 d are lowconcentration impurity regions to be LDD (Lightly Doped Drain) regions.The n-type impurity region 145 a and the n-type impurity region 145 bcovered with the first gate electrode layer 122 with the gate insulatinglayer 107 interposed therebetween are Lov regions which can alleviate anelectric field around a drain and suppress a degradation of an oncurrent due to a hot carrier. As a result, a thin film transistorcapable of high speed operation can be formed. On the other hand, thethird n-type impurity region 148 a, the third n-type impurity region 148b, the third n-type impurity region 148 c, and the third n-type impurityregion 148 d are formed in Loff regions which are not covered with thegate electrode layer 127 and the gate electrode layer 128, therefore,there are effects that an electric field around a drain can bealleviated and degradation due to a hot carrier injection can beprevented as well as an off current can be reduced. As a result, asemiconductor device with high reliability and low power consumption canbe formed.

Subsequently, the mask 153 a, the mask 153 b, the mask 153 c, and themask 153 d are removed and a mask 155 a and a mask 155 b to cover thesemiconductor layer 103 and the semiconductor layer 105 are formed. Byadding an impurity element 154 which impart p type with the mask 155 a,the mask 155 b, the gate electrode layer 117 and the gate electrodelayer 129 as masks, a first p-type impurity region 160 a, a first p-typeimpurity region 160 b, a first p-type impurity region 163 a, a firstp-type impurity region 163 b, a second p-type impurity region 161 a, asecond p-type impurity region 161 b, a second p-type impurity region 164a, and a second p-type impurity region 164 b are formed. In thisembodiment mode, boron (B) is used as an impurity element, therefore,doping is performed using diborane (B₂H₆) (the composition rate of B is15%) as a doping gas containing an impurity element at a gas flow rateof 70 sccm, a beam current of 180 μA/cm, an acceleration voltage of 80kV, and an adding dosage of 2.0×10¹⁵ ions/cm². Here, doping is performedso that the first p-type impurity region 160 a, the first p-typeimpurity region 160 b, the first p-type impurity region 163 a, the firstp-type impurity region 163 b, the second p-type impurity region 161 a,the second p-type impurity region 161 b, the second p-type impurityregion 164 a, and the second p-type impurity region 164 b contain theimpurity element which imparts p type at a concentration of about 1×10²⁰to 5×10²¹/cm³. In this embodiment mode, the second p-type impurityregion 161 a, the second p-type impurity region 161 b, the second p-typeimpurity region 164 a, and the second p-type impurity region 164 b areformed in a self-aligned manner by reflecting the shapes of the gateelectrode layer 117 and the gate electrode layer 129 to have a lowerconcentration than the first p-type impurity region 160 a, the firstp-type impurity region 160 b, the first p-type impurity region 163 a,and the first p-type impurity region 163 b. Further, a channel formingregion 162 is formed in the semiconductor layer 103 and a channelforming region 165 is formed in the semiconductor layer 106.

The second n-type impurity region 144 a, the second n-type impurityregion 144 b, the second n-type impurity region 147 a, the second n-typeimpurity region 147 b, and the second n-type impurity region 147 c arehigh concentration n-type impurity regions which function as sources ordrains. On the other hand, the second p-type impurity region 161 a, thesecond p-type impurity region 161 b, the second p-type impurity region164 a, and the second p-type impurity region 164 b are low concentrationimpurity regions to be LDD (LightlyDoped Drain) regions. The secondp-type impurity region 161 a, the second p-type impurity region 161 b,the second p-type impurity region 164 a, and the second p-type impurityregion 164 b covered with the first gate electrode layer 121 and thefirst gate electrode layer 126 with the gate insulating layer 107interposed therebetween are Lov regions which can alleviate an electricfield around a drain and suppress a degradation of an on current due toa hot carrier.

The mask 155 a and the mask 155 b are removed by O₂ ashing or a resistpeeling solution, thereby the oxide film is also removed. After that, aninsulating film, namely sidewalls may be formed so as to cover sides ofthe gate electrode layers. The sidewalls can be formed of an insulatingfilm containing silicon using a plasma CVD method or a low pressure CVD(LPCVD) method.

In order to activate the impurity element, heat treatment, strong lightirradiation, or laser light irradiation may be performed. At the sametime as the activation, plasma damage to the gate insulating layer andplasma damage to an interface between the gate insulating layer and thesemiconductor layer can be recovered.

Subsequently, an interlayer insulating layer which covers the gateelectrode layer and the gate insulating layer is formed. In thisembodiment mode, it is formed with a stacked-layer structure of theinsulating film 167 and the insulating film 168 (see FIG. 4(A)). Asilicon nitride oxide film is formed as the insulating film 167 with athickness of 200 nm and an oxynitride insulating film is formed as theinsulating film 168 with a thickness of 800 nm to be a stacked-layerstructure. Further, a stacked-layer structure of three layers may beemployed by forming a silicon oxynitride film with a thickness of 30 nm,forming a silicon nitride oxide film with a thickness of 140 nm, andforming a silicon oxynitride film with a thickness of 800 nm whilecovering the gate electrode layer and the gate insulating layer. In thisembodiment mode, the insulating film 167 and the insulating film 168 arecontinuously formed using a plasma CVD method similarly to the basefilm. The insulating film 167 and the insulating film 168 are notlimited to a silicon nitride film and may be a silicon nitride oxidefilm, a silicon oxynitride film, or a silicon oxide film using asputtering method or a plasma CVD method. Alternatively, a single-layerstructure or a stacked-layer structure of three or more layers of otherinsulating film containing silicon may be employed as well.

Further, thermal treatment is performed in a nitrogen atmosphere at 300to 550° C. for 1 to 12 hours, thereby a step of hydrogenating thesemiconductor layer is performed, or preferably performed at 400 to 500°C. This step is a step of terminating dangling bonds in thesemiconductor layer with hydrogen contained in the insulating film 167which is an interlayer insulating layer. In this embodiment mode, heattreatment is performed at 410° C. (° C.).

The insulating film 167 and the insulating film 168 can be formed of amaterial selected from aluminum nitride (AlN), aluminum oxynitride(AlON), aluminum nitride oxide (AlNO) in which nitrogen content is morethan oxygen content, aluminum oxide, diamond-like carbon (DLC), anitrogen-containing carbon film (CN), polysilazane and other substancecontaining an inorganic insulating material. Further, a siloxanematerial (inorganic siloxane and organic siloxane) may be used as well.Moreover, an organic insulating material may be used, and polyimide,acrylic, polyamide, polyimide amide, resist, or benzocyclobutene can beused as an organic material. A coated film with a superior planarity bya coating method may be used as well.

Subsequently, contact holes (openings) reaching the semiconductor layerare formed in the insulating film 167 and the insulating film 168, andthe gate insulating layer 107 using a mask composed of resist. Etchingmay be performed once or a plurality of times in accordance with aselection ratio of a material to be used. In this embodiment mode, firstetching is performed with a condition that a selection ratio can beobtained between the insulating film 168 which is a silicon oxynitridefilm, the insulating film 167 which is a silicon nitride oxide film andthe gate insulating layer 107, thereby the insulating film 168 isremoved. Then, the insulating film 167 and the gate insulating layer 107are removed by second etching to form openings reaching the first p-typeimpurity region 160 a, the first p-type impurity region 160 b, the firstp-type impurity region 163 a, the first p-type impurity region 163 b,the second n-type impurity region 144 a, the second n-type impurityregion 144 b, the second n-type impurity region 147 a and the secondn-type impurity region 147 b which are source regions or drain regions.In this embodiment mode, the first etching is performed by wet etchingwhile the second etching is performed by dry etching. A fluorine-basedsolution such as a mixed solution containing ammonium hydrogen fluorideand ammonium fluoride may be used as an etchant of wet etching. As anetching gas, a chlorine-based gas typified by Cl₂, BCl₃, SiCl₄, CCl₄, orthe like, a fluorine-based gas typified by CP₄, SF₆, NF₃, or the like,or O₂ can be appropriately used. Further, an inert gas may be added toan etching gas to be used. As an inert element to be added, one or aplurality of elements selected from He, Ne, Ar, Kr and Xe can be used.

A conductive film is formed so as to cover the openings, and theconductive film is etched to form a source electrode layer or a drainelectrode layer 169 a, a source electrode layer or a drain electrodelayer 169 b, a source electrode layer or a drain electrode layer 170 a,a source electrode layer or a drain electrode layer 170 b, a sourceelectrode layer or a drain electrode layer 171 a, a source electrodelayer or a drain electrode layer 171 b, a source electrode layer or adrain electrode layer 172 a, a source electrode layer or a drainelectrode layer 172 b, and a wiring layer 156 which are electricallyconnected to a portion of each source region or drain region. The sourceelectrode layer or drain electrode layer can be formed by forming aconductive film by a PVD method, a CVD method, a vapor deposition methodand the like, and then etching the conductive film into a desired shape.Further, a conductive layer can be selectively formed in a predeterminedplace by a droplet discharge method, a printing method, an electrolyticplating method and the like. Furthermore, a reflow method and adamascene method may be used as well. The material of the sourceelectrode layer or drain electrode layer is formed using a metal such asAg, Au, Cu, Ni, Pt, Pd, Ir, Rh, W, Al, Th, Mo, Cd, Zn, Fe, Ti, Si, Ge,Zr, and Ba, an alloy thereof or a metal nitride thereof. Further, astacked-layer structure of these may be used as well. In this embodimentmode, titanium (Ti) is formed with a thickness of 100 nm, an alloy ofaluminum and silicon (Al—Si) is formed with a thickness of 700 nm, andtitanium (Ti) is formed with a thickness of 200 nm, and then patternedinto a desired shape.

By the aforementioned steps, an active matrix substrate can be formed inwhich a p-channel thin film transistor 173 having a p-type impurityregion in a Lov region and an n-channel thin film transistor 174 havingan n-channel impurity region in a Lov region are formed in theperipheral driver circuit region 204, a conductive layer 177 is formedin the connecting region, and a multi-channel type n-channel thin filmtransistor 175 having an n-type impurity region in a Loff region and ap-channel thin film transistor 176 having a p-type impurity region in aLov region are formed in the pixel region 206 (see FIG. 4(B)).

Then, the active matrix substrate can be used for a light emittingdevice having a self-luminous element, a liquid crystal display devicehaving a liquid crystal element, and other display devices. Moreover,the active matrix substrate can be used for a semiconductor device suchas various processors typified by a CPU (Central Processing Unit) and acard which incorporates an ID chip.

The invention is not limited to this embodiment mode, and a thin filmtransistor may have a single-gate structure in which one channel formingregion is formed, a double-gate structure in which two channel formingregions are formed, or a triple-gate structure in which three channelforming regions are formed. Further, a thin film transistor in theperipheral driver circuit region may have a single-gate structure, adouble-gate structure, or a triple-gate structure as well.

Note that the invention is not limited to the method for manufacturing athin film transistor described in this embodiment mode, and can beapplied to a top gate type (planar type), a bottom gate type (invertedstagger type), or a dual gate type in which two gate electrode layersare arranged at the top and bottom of a channel region with a gateinsulating film interposed therebetween, or other structures.

Subsequently, an insulating film 180 and an insulating film 181 areformed as a second interlayer insulating layer (see FIG. 5(A)). FIG. 5shows a manufacturing step of a display device, in which a separatingregion 201 for separating by scribing, an external terminal connectingregion 202 which is an attached portion of an FPC, a wiring region 203as a lead wiring region of a peripheral portion, a peripheral drivercircuit region 204, a connecting region 205, and a pixel region 206 areprovided. The wiring region 203 is provided with a wiring 179 a and awiring 179 b, and the external terminal connecting region 202 isprovided with a terminal electrode layer 178 connected to an externalterminal.

The insulating film 180 and the insulating film 181 can be formed of amaterial selected from silicon oxide, silicon nitride, siliconoxynitride, silicon nitride oxide, aluminum nitride (AlN), aluminumoxynitride (AlON), aluminum nitride oxide (AlNO) in which nitrogencontent is more than oxygen content, aluminum oxide, diamond-like carbon(DLC), a nitrogen-containing carbon film (CN), PSG (phosphorous silicateglass), BPSG (boron phosphorous silicon glass), alumina film,polysilazane, and other substance containing an inorganic insulatingmaterial. Further, a siloxane resin may be used as well. Note that thesiloxane resin corresponds to a resin including a Si—O—Si bond. Siloxaneis composed of a skeleton structure formed by the bond of silicon (Si)and oxygen (O), in which an organic group containing at least hydrogen(such as man alkyl group or aromatic hydrocarbon) is used as asubstituent. Alternatively, a fluoro group may be used as thesubstituent. Further alternatively, a fluor group and an organic groupcontaining at least hydrogen may be used as the substituent. Moreover,an organic insulating material may be used, and polyimide, acrylic,polyamide, polyimide amide, resist, benzocyclobutene, or a lowdielectric organic insulating material can be used as an organicmaterial which is either photosensitive or non-photosensitive.

In this embodiment mode, a silicon oxynitride film is formed with athickness of 200 an as the insulating film 180 using a CVD method. As aninterlayer insulating layer provided for planarization, high heatresistance, high insulation, and high planarization ratio e required sothat it is preferable to use a coating method typified by a spin coatingmethod as a method for forming of the insulating film 181.

In this embodiment mode, a coated film using a siloxane resin materialis used as a material of the insulating film 181. A film after beingfired can be called a silicon oxide film (SiO_(x))) (x, y=1, 2 . . . )including an alkyl group. The silicon oxide film including the alkylgroup can resist to even best treatment of 300° C. or higher.

The insulating film 180 and the insulating film 181 can be formed byadopting dipping, spray application, a doctor knife, a roll coater, acurtain coater, a knife coater, a CVD method, a vapor deposition methodand the like. The insulating film 180 and the insulating film 181 may beformed by a droplet discharge method. In the case of using the dropletdischarge method, a material liquid can be saved. Further, a method fortransferring or drawing a pattern similarly to the droplet dischargemethod, for example a printing method (a method for forming a patternsuch as screen printing and offset printing) and the like can be used aswell.

Subsequently, as shown in FIG. 5(B), openings are formed in theinsulating film 180 and the insulating film 181 which are the secondinterlayer insulating layer. The insulating film 180 and the insulatingfilm 181 are required to be etched in a wide area in the connectingregion 205, the wiring region 203, the external terminal connectingregion 202, the separating region 201 and the like. However, in thepixel region 206, an opening area is extremely small and minute comparedto an opening area of the connecting region 205 and the like. Therefore,a photolithography step of forming an opening in the pixel region and aphotolithography step of forming an opening in the connecting region areprovided to widen margin of etching conditions. As a result, yield canbe improved. Further, by widening the margin of etching conditions, acontact hole formed in the pixel region can be formed at high precision.

Specifically, wide area openings are formed in the insulating film 180and the insulating film 181 which are provided in a part of theconnecting region 205, the wiring region 203, the external terminalconnecting region 202, the separating region 201, and the peripheraldriver circuit region 204. Therefore, a mask is formed to cover theinsulating film 180 and the insulating film 181 in the pixel region 206,a part of the connecting region 205, and a part of the peripheral drivercircuit region 204. A parallel plate RIE device and an ICP etchingdevice can be used for etching. Note that etching time may be longenough to over etch the wiring layer and the first interlayer insulatinglayer. With such degree of overetching, thickness variation and etchingrate variation in a substrate can be reduced. In this manner, an opening182 and an opening 183 are formed in the connecting region 205 and theexternal terminal connecting region 202 respectively.

After that, as shown in FIG. 5(B), a minute opening, that is a contacthole is formed in the insulating film 180 and the insulating film 181 ofthe pixel region 206 (see FIG. 5(C)). At this time, a mask is formed tocover the pixel region 206, a part of the connecting region 205, theperipheral driver circuit region 204, and the pixel region 206. The maskis a mask for forming an opening in of the pixel region 206 and a minuteopening is provided in a predetermined place. As such a mask, forexample, a resist mask can be used.

Then, the insulating film 180 and the insulating film 181 are etchedusing a parallel plate RIE device. Note that etching time may be longenough to overetch the wiring layer and the first interlayer insulatinglayer. With such degree of overetching in this manner, thicknessvariation and etching rate variation in a substrate can be reduced.

Further, an ICP device may be used for an etching device. In the abovesteps, an opening 184 reaching the source electrode or the drainelectrode layer 172 a is formed in the pixel region 206. In theinvention, the source electrode or the drain electrode layer 172 a isformed to cover the gate electrode layer 126 of the thin film transistor176 in which many thin films are stacked with a large total thicknesswith the insulating film 167 and the insulating film 168 interposedtherebetween. Therefore, the opening 184 is not required to be openedwith a deep thickness, thereby an opening step can be shortened toimprove controllability. Further, since an electrode layer formed in theopening is also not required to widely cover an opening with a largeangle, excellent coverage can be obtained and reliability can beimproved.

In this embodiment mode, although description is made on the case wherethe insulating film 180 and the insulating film 181 are etched with themask which covers a part of the connecting region 205, the wiring region203, the external terminal connecting region 202, the separating region201, and the peripheral driver circuit region 204 and is provided with apredetermined opening in the pixel region 206, the invention is notlimited thereto. For example, since the opening of the connecting region205 has a large area, an etching amount thereof is large Such opening ofa large area may be etched a plurality of times. Further, in the case offorming a deep opening compared to other opening portions, etching maybe performed a plurality of times similarly. Therefore, the insulatingfilm 180 and the insulating film 181 may be etched using the maskprovided with a predetermined opening in the connecting region 205 andthe pixel region 206 while covering only the insulating film 180 and theinsulating film 181 in a part of the wiring region 203, the externalterminal connecting region 202, the separating region 201, and theperipheral driver circuit region 204. In the case of etching using sucha mask, the insulating film 180 and the insulating film 181 in theconnecting region 205 are etched in further depth to be etched until theinsulating film 168 is exposed.

Further, in this embodiment mode, although the formation of the openingsin the insulating film 180 and the insulating film 181 is separatelyconducted a plurality of times as shown in FIGS. 5(B) and (C), theformation of the openings in the insulating film 180 and the insulatingfilm 181 may be performed by one etching step. In this case, etching isperformed using an ICP device with an ICP power of 7000 W, a bias powerof 1000 W, a pressure of 0.8 Pascal (Pa), CF₄ of 240 sccm and O₂ of 160sccm as etching gas. The bias power is preferably 1000 to 4000 W. Sinceopenings can be formed by one etching step, there is an advantage inthat a step can be simplified.

Subsequently, a first electrode layer 185 (also referred to as a pixelelectrode layer) is formed in contact with the source electrode layer ordrain electrode layer 172 a. The first electrode layer functions as ananode or cathode, and may be formed using an element selected from Ti,Ni, W, Cr, Pt, Zn, Sn, In, or Mo, TiN, TiSi_(X)N_(Y), WSi_(X), WN_(X),WSi_(X)N_(Y), NbN, a film which is mainly formed of an alloy material orcompound material containing the aforementioned material as a maincomponent, or stacked films thereof with a total thickness of a range of100 to 800 nm.

A structure in this embodiment mode includes a light emitting elementused as a display element and light from the light emitting element isextracted from the first electrode layer 185 side, therefore, the firstelectrode layer 185 has a light transmitting property. A transparentconductive film is formed as the first electrode layer 185 and thenetched into a desired shape to form the first electrode layer 185.Indium tin oxide containing silicon oxide (also referred to as indiumtin oxide containing silicon oxide and hereinafter referred to as“ITSO”), zinc oxide, tin oxide, indium oxide and the like may be used asthe first electrode layer 185 used in the invention. Besides, atransparent conductive film such as indium oxide zinc oxide alloy inwhich zinc oxide (ZnO) of 2 to 20% is mixed in indium oxide and the likecan be used. As the first electrode layer 185, a titanium nitride filmor a titanium film may be used as well as the aforementioned transparentconductive film. In this case, after forming a transparent conductivefilm, a titanium nitride film or a titanium film is formed with athickness enough to transmit light (preferably about 5 nm to 30 nm). Inthis embodiment mode, ITSO using indium tin oxide and silicon oxide isused as the first conductive layer 185. In this embodiment mode, an ITSOfilm is formed with a thickness of 185 nm using a target in whichsilicon oxide (SiO₂) of 1 to 10 [%] is mixed in indium tin oxide at anAr gas flow rate of 120 sccm, an O₂ gas flow rate of 5 sccm, a pressureof 0.25 Pa, and a power of 3.2 kW by a sputtering method. The firstelectrode layer 185 may be swabbed and polished with a polyvinylalcohol-based porous media by a CMP method to planarize the surfacethereof. Further, after the polish using a CMP method, UV lightirradiation, oxygen plasma treatment and the like may be applied to thesurface of the first electrode layer 185.

After forming the first electrode layer 185, heat treatment may beperformed. By the heat treatment, moisture contained in the firstelectrode layer 185 is discharged. Therefore, the first electrode layer185 does not generate degasification and the like, thereby a lightemitting material is not deteriorated even when a light emittingmaterial which is easily deteriorated by moisture is formed over thefirst electrode layer. Thus, a display device with high reliability canbe manufactured. In this embodiment mode, ITSO is used for the firstelectrode layer 185, thereby not crystallized unlike ITO (indium oxidetin oxide alloy) even when baked and remains in an amorphous state.Therefore, ITSO has higher planarity than ITO and does not easilygenerate a short circuit with a cathode even when a layer containing anorganic compound is thin.

Subsequently, an insulator (insulating layer) 186 (also referred to as abank, a partition, a barrier, an embankment, and the like) is formed tocover an end portion of the first electrode layer 185, and the sourceelectrode layers or drain electrode layers (see FIG. 6(B)). Further, aninsulator (insulating layer) 187 a and an insulator (insulating layer)187 b are formed in the external terminal connecting region 202 by thesame step.

In order to perform a full color display, electroluminescent layers foremitting light of RGB are required to be formed separately when formingan electroluminescent layer over the first electrode layer. Therefore,when forming an electroluminescent layer of another color, the pixelelectrode layer (the first electrode layer) for the color is coveredwith a mask. The mask may in a form of a film formed of a metal materialand the like. At this time, although the mask is provided over theinsulator 186 which becomes a partition and supported, the mask maycontact the pixel electrode layer by a deflection or a twist, and maycause a crack in the pixel electrode layer. When the pixel electrodelayer has a defect in shapes by a crack and the like, a light emissiondefect, a display defect and the like are caused to decrease imagequality. Therefore, reliability and performance may also be degraded.

In this embodiment mode, a spacer 199 is formed with an equivalentthickness to that of the insulator 186 over the first electrode layer185 which is a pixel electrode layer. By the spacer 199, a mask which isused in vapor deposition of the electroluminescent layer is supported sothat the mask is not in contact with the first electrode layer.Therefore, a shape defect of the first electrode layer by the mask isprevented so that the first electrode layer does not generate a lightemission defect and a display defect, and a display device with highreliability and high image quality can be provided.

In this embodiment mode, although the spacer 199 is formed of the samematerial and by the same step as the insulator 186 which is a partition,another step may be employed as well. The shape and size of the spacerare not limited, and they may be set in consideration of the size,aperture ratio and the like of the pixel region. In this embodimentmode, the spacer has a columnar shape of which a top portion has a roundshape like a hemisphere as shown in FIG. 6(B), of which height is 1 to 2μm (preferably 1 to 1.5 μm).

An example of the shape of a spacer is described with reference to FIGS.31 and 28. As shown in FIGS. 28 and 31, an insulator (insulating layer)which is a partition and a spacer may be continuously connected to beformed. FIGS. 31(A), (C), 28(A) and (C) are top plan views of a pixelregion. FIGS. 31(B), (C), 28(B) and (D) are cross sectional diagramsalong lines X1-Y1, X2-Y2, X3-Y3, and X4-Y4 of FIGS. 31(A), (C), 28(A)and (C) respectively. In FIGS. 31(A) and (B), a first electrode layer607 which is a pixel electrode layer is formed over a substrate 600, abase film 601 a, a base film 601 b, a gate insulating layer 602, aninsulating film 603, an insulating film 604, an insulating film 605, andan insulating film 606. An insulator (insulating layer) 608 which is apartition is formed to cover an end portion of the first electrode layer607, and a spacer 609 is formed of the same material and by the samestep as the insulator 608.

In FIGS. 31(A) and 31(B), the spacer 609 is formed to be in contact withthe insulator 608. The spacer 609 is continuously formed so as to crossover the first electrode layer, the first electrode layer 607diagonally. When continuously forming the spacer 609 in this manner, amask is always supported by the spacer 609 while being moved, thus itcan be prevented that the mask contacts the first electrode layer 607and the first electrode layer 607 has a defect in shapes.

In FIGS. 31(C) and (D), a first electrode layer 617 which is a pixelelectrode layer is formed over a substrate 610, a base film 611 a, abase film 611 b, a gate insulating layer 612, an insulating film 613, aninsulating film 614, an insulating film 615, and an insulating film 616.An insulator (insulating layer) 618 which is a partition is formed tocover an end portion of the first electrode layer 617, and a spacer 619is formed of the same material and by the same step as the insulator618.

In FIGS. 31(C) and (D), the spacer 619 is formed to be in contact withthe insulator 618. The spacer 619 is continuously formed at two placesso as to cross over the first electrode layer, the first electrode layer617 in a short side direction thereof. When continuously forming thespacer 619 at a plurality of places in this manner, a mask is alwayssupported by the spacer 619 while being moved, thus it can be preventedthat the mask contacts the first electrode layer 617 and the firstelectrode layer 617 has a defect in shapes.

In FIGS. 28(A) and (B), a first electrode layer 627 which is a pixelelectrode layer is formed over a substrate 620, a base film 621 a, abase film 621 b, a gate insulating layer 622, an insulating film 623, aninsulating film 624, an insulating film 625, and an insulating film 626.An insulator (insulating layer) 628 which is a partition is formed tocover an end portion of the first electrode layer 627, and a spacer 629is formed of the same material and by the same step as the insulator628.

In FIGS. 28(A) and (B), the spacer 629 is formed to be in contact withthe insulator 628. The spacer 629 is continuously formed so as to crossover the first electrode layer, the first electrode layer 627 in a longside direction and a short side direction thereof in a lattice shape.When continuously forming the spacer 629 in a lattice shape in thismanner, a mask is always supported by the spacer 629 while being moved,thus it can be prevented that the mask contacts the first electrodelayer 627 and the first electrode layer 627 has a defect in shapes.

In FIGS. 28(C) and (D), a first electrode layer 637 which is a pixelelectrode layer is formed over a substrate 630, a base film 631 a, abase film 631 b, a gate insulating layer 632, and an insulating film633, an insulating film 634, an insulating film 635, and an insulatingfilm 636. An insulator (insulating layer) 638 which is a partition isformed to cover an end portion of the first electrode layer 637, and aspacer 639 is formed of the same material and by the same step as theinsulator 638.

In FIGS. 28(C) and (D), the spacer 639 is formed to be in contact withthe insulator 638. The spacer 639 is formed so as to obliquely crossover the first electrode layer 637 a plurality of times relatively to aninterface with the insulator 638. In this embodiment mode, an anglebetween a short axis of the interface between the first electrode layer637 and the insulator and the spacer 639 is 45°. When continuouslyforming the spacer 639 in this manner, a mask is always supported by thespacer 639 while being moved, thus it can be prevented that the maskcontacts the first electrode layer 637 and the first electrode layer 637has a defect in shapes.

As shown in FIG. 28(B), the spacer 629 has a tapered shape. In thismanner, the spacer may be in an approximate rectangular parallelepipedas shown in FIGS. 31(B) and 28(D) or may have various shapes such as acolumnar shape, a prism, a cone, a pyramid, and a tapered shape.

The spacer is formed in contact with the insulator (insulating layer)which is a partition in FIGS. 31 and 28, however, it may be separatedfrom the insulator without contact.

The spacer can be formed of an inorganic insulating material such assilicon oxide, silicon nitride, silicon oxynitride, aluminum oxide,aluminum nitride, and aluminum oxynitride, or acrylic acid, methacrylicacid, and a derivative thereof, or heat-resistant polymers such aspolyimide (polyimide), aromatic polyamide, and polybenzoimidazole(polybenzoimidazole), or an insulating material such as a siloxaneresin. In this embodiment mode, acrylic is used for the spacer 199.

In this embodiment mode, acrylic is used for the insulator 186. Further,if the insulator 186 is formed using the same material and by the samestep as the insulating film 181, manufacturing cost can be reduced.Moreover, cost can be reduced by using a coating deposition apparatus,an etching apparatus and the like in common.

The insulator 186 can be formed of an inorganic insulating material suchas silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide,aluminum nitride, and aluminum oxynitride, or acrylic acid, methacrylicacid, a derivative thereof, or a heat-resistant polymers such aspolyimide (polyimide), aromatic polyamide, or polybenzimidazole(polybenzimidazole), or an insulating material such as a siloxane resin.Alternatively, the insulator 186 may be formed using a photosensitive ornon-photosensitive material such as acrylic or polyimide. The insulator186 preferably has a shape that a curvature radius thereof continuouslychanges. Accordingly, coverage of an electroluminescent layer 188 and asecond electrode layer 189 to be formed thereover is improved.

In the connecting region 205, the insulator 186 is formed to cover theend portion of the insulating film 180 and the insulating film 181 on aside face of the opening 182. Due to steep steps of the end portions ofthe insulating film 180 and the insulating film 181 each formed to havea step by patterning the coverage of the second electrode layer 189 tobe stacked thereover is unfavorable. Therefore, as in the invention, bycovering the steps in the periphery of the opening with the insulator186 to planarize the steps, the coverage of the second electrode layer189 to be stacked can be improved. In the connecting region 205, awiring layer formed of the same material and by the same step as thesecond electrode layer is electrically connected to the wiring layer156. In this embodiment mode, the second electrode layer 189 iselectrically connected to the wiring layer 156 directly, however, theymay be electrically connected with another wiring interposedtherebetween.

In the invention, a spacer 198 is formed over the insulator 186 whichfunctions as a partition. Similarly to the spacer 199 formed over thepixel electrode layer, a mask which is used in vapor deposition of theelectroluminescent layer is supported by the spacer 198 so that thisspacer is also not in contact with the first electrode layer. It ispreferable that the spacer 198 formed over the insulator 186 be notformed over a thin film transistor, which can prevent a defect such aselectrostatic discharge damage. Note that the spacer 199 formed over thepixel electrode layer and the spacer 198 finned over the insulator 186can also be called a first spacer and a second spacer respectively.Therefore, a mask is supported by the first spacer and the secondspacer, thereby the first electrode layer is prevented from having adefect in shapes by the mask so that the first electrode layer does notgenerate a light emission defect and a display defect. Thus, a displaydevice with high reliability and high image quality can be provided.

The insulator 186, the spacer 199, and the spacer 198 can be formed bydipping, spray application, a doctor knife, a roll coater, a curtaincoater, a knife coater, a CVD method, a vapor deposition method and thelike. The insulator 186, the spacer 199, and the spacer 198 may beformed by a droplet discharge method. In the case of using the dropletdischarge method, a material liquid can be saved. Further, a method fortransferring or drawing a pattern like the droplet discharge method, forexample a printing method (a method for forming a pattern such as screenprinting and offset printing) and the like can be used as well.

Moreover, after forming the insulator 186, the spacer 199, and thespacer 198, the surfaces thereof may be pressed by pressure to beplanarized so as to increase the planarity. As a method for pressing, aroller type press may be scanned over the surface to reduce an asperity,or the surface may be perpendicularly pressed with a plane board typepress. In pressing, a heating step may be performed. Further, thesurface may be softened or melted with a solvent and the like and theasperity of the surface may be removed with an air knife. Furthermore, aCMP method may be used to polish.

The spacer 198 may be formed of the same material and by the same step athe spacer 199, or may be formed by another step as in this embodimentmode. The shape and size of the spacer are not limited, and they may beset in consideration of the size, a mask material, thickness, and thelike of the pixel region. In this embodiment mode, the spacer has acolumnar shape of which a top portion has a round shape like ahemisphere as shown in FIG. 6(B), of which height is 1 to 3 μm(preferably 1.5 or more and 2 μm or less). Further, in the case offorming the spacer 198 and the spacer 199 with different materials andsteps, spacers having different shapes and thickness can be freelyformed. In this embodiment mode, although a height from the substrate100 to the top surface of the spacer 198 and a height from the substrate100 to the top surface of the spacer 199 are different from each other,they can be approximately the same heights if the spacer 198 and thespacer 199 are formed using a coated film or the like with highplanarity after forming the insulator 186 after forming the insulator.In such a case, a region of a mask supported by a spacer is increased,therefore, the mask can be set further stably.

The insulator 186 and the spacer 198 are stacked to be formed indifferent shapes, therefore, a material which has a high selection ratioin etching is preferably used. For example, when using an inorganicmaterial for the insulating layer 186 and an organic material for thespacer 198, the selection ratio can be high to be patterned in anexcellent shape.

Moreover, in order to further improve the reliability, it is preferableto perform degasification by vacuum heating before forming theelectroluminescent layer (layer containing an organic compound) 188. Forexample, it is desirable to perform beat treatment for removing gascontained in the substrate in a low pressure atmosphere or an inert gasatmosphere at 200 to 400° C. or preferably 250 to 350° C. beforeperforming vapor deposition of an organic compound material. Further, itis preferable to form the electroluminescent layer 188 by a vacuum vapordeposition method or a droplet discharge method under low pressurewithout air exposure. By this thermal treatment, moisture contained inor attached to a conductive film to be the first electrode layer or aninsulating layer (partition) can be discharged. This heat treatment canbe combined with a prior heating step as long as the substrate can betransferred in a vacuum chamber without breaking the vacuum. Therefore,the prior heating step may be performed once after forming an insulatinglayer (partition). Here, the interlayer insulating film and theinsulator (partition) are formed with a substance having highly heatresistance, thereby a beat treatment step can be sufficiently performedfor improving the reliability.

The electroluminescent layer 188 is formed over the first electrodelayer 185. Note that although only one pixel is shown in FIG. 1,electric electrode layers corresponding to the respective colors of R(red), G (green), and B (blue) are formed separately in this embodimentmode. In this embodiment mode, each of FIGS. 32 and 29 shows a state ofselectively forming each material which shows the light emission of red(R), green (G), or blue (B) as the electroluminescent layer 188 by avapor deposition method using a vapor deposition mask and the like.FIGS. 32 and 29 show a step of forming a material which shows red lightemission. In this embodiment mode, a method is used by which each coloris formed using a different vapor deposition apparatus or a vapordeposition mask, however, the light emitting materials of three colorscan be formed in the same chamber by moving one mask.

FIG. 29(A) is a schematic diagram of a vapor deposition step and FIG.29(B) is a diagram of an element substrate and a vapor deposition maskseen from a vapor deposition source 761 side. As shown in FIG. 29(A), amagnetic body 765 for controlling the position of a mask and detachingthe mask from and attaching the mask to an element substrate 764, theelement substrate 764, a mask 763, a shutter 762, and the vapordeposition source 761 are provided in a chamber 760 of a vapordeposition apparatus. The magnetic body 765 is moved in a direction ofan arrow 770 by a control apparatus 772, and an alignment of the elementsubstrate 764 and the mask 763 is observed by a camera 771 a and acamera 771 b. Besides, a heater for heating the vapor deposition source,a quartz oscillator for controlling a film thickness, a controlapparatus for controlling the temperature and position at each portion,and the like are provided in the vapor deposition apparatus. The elementsubstrate 764 is provided with an element side facing down toward thevapor deposition source 761, and the mask 763 is provided close to theelement substrate 764 and the shutter 762 for controlling the start andfinish of vapor deposition is provided between the mask 763 and thevapor deposition source 761 toward the vapor deposition source 761 side.The mask 763 is formed of a metal material and has a magnetic property,therefore, controlling the upper and lower positions of the mask 763shown in the direction of the arrow 770 is performed by the magneticbody 765 formed of a magnetic material.

FIG. 29(B) shows the mask 763 and the element substrate 764 seen fromthe vapor deposition source 761 side. The mask 763 is set to be closelyattached onto the element side of the element substrate 764 by themagnetic force of the magnetic body 765. Further, an alignment of eachpixel may be any one of arrangement methods of a stripe arrangement inwhich pixels corresponding to red, green, and blue are arranged instripes, a delta arrangement in which the pixels are shifted by a halfpitch per one line, and a mosaic arrangement in which sub-pixelscorresponding to rod, green, and blue are arranged obliquely. The stripearrangement is suitable for displaying a line, a figure, text, and thelike, therefore, it is preferably applied to a monitor. Further, a morenatural image than the stripe arrangement can be obtained with themosaic arrangement, therefore, it is preferably applied to a televisiondevice and the like. Furthermore, a natural image display can also beobtained with the delta arrangement, therefore, it is preferably appliedto a television device and the like. The television device is alsocalled television simply.

In this embodiment mode, the stripe arrangement is used as thearrangement of pixels. As shown in FIG. 29(B), a slit type mask having aslit shape opening such as an opening 769 a and an opening 769 b is usedfor the mask 763. With the slit type mask, all pixels which emit a coloramong colors can be formed at the same time, thereby productivity ishigh. Other than the slit type mask, a slot type mask having an openingcorresponding to each pixel in a slot shape without a continuous openinglike the slit type mask may be used as well. There is a case where theslot type mask requires a plurality of times (twice or more) of vapordepositions for each color in the pixels of the stripe arrangement,however, the slot type mask is suitable for the delta arrangement inwhich an arrangement is not linear, and mask rigidity is high since oneopenings small.

A pixel electrode layer 766 a to be a pixel for displaying red color, apixel electrode layer 766 b to be a pixel for displaying green color,and a pixel electrode layer 766 c to be a pixel for displaying bluecolor are provided on the element substrate 764. FIG. 29 shows the caseof forming a light emitting material for red color, therefore, the mask763 is provided so that the opening 769 a and the opening 769 bcorrespond to the pixel electrode layers for displaying red color.

According to the invention, spacers are formed over a pixel electrodelayer and over an insulator (insulating layer) which covers an endportion of each pixel electrode layer and functions as a partition.Accordingly, a spacer 767 and a spacer 768 are provided over a pixelelectrode layer and an insulator (insulating layer) shown in FIG. 29(B)as well. The mask 763 is supported by the spacer 767 and the spacer 768,therefore, it can be prevented that the mask 763 contacts the pixelelectrode layer 766 a, the pixel electrode layer 766 b, and the pixelelectrode layer 766 c even when the rigidity of the mask 763 is weak,and twist, deflection and the like occur due to a magnetic force,gravitation and the like. Therefore, damage is not caused to the pixelelectrode layer, thereby favorable light emission and display can beperformed. Even in the case where a substrate has a large area and highresolution, and thus an opening of a mask becomes large and a shieldportion is thinned, which leads to decrease the rigidity of the maskitself and difficulty in accurately controlling the position of themask, the mask can be supported by the spacers and provided in a desiredposition.

With reference to FIG. 32, description is made on a positionalrelationship between an element substrate and a mask in detail. FIG. 32is a cross sectional diagram of an element substrate and a mask in vapordeposition which is seen with a vapor deposition source on the upperside. Therefore, a state is inverted to the element substrate shown inFIG. 29(A). In FIG. 32, a thin film transistor 651 a, a thin filmtransistor 651 b, a thin film transistor 651 c, and a thin filmtransistor 651 d are connected to a first electrode layer 652 a, a firstelectrode layer 652 b, a first electrode layer 652 c, and a firstelectrode layer 652 d which are pixel electrode layers. Each end portionof the first electrode layers is covered with an insulator (insulatinglayer) 653 a, an insulator (insulating layer) 653 b, an insulator(insulating layer) 653 c, and an insulator (insulating layer) 653 dwhich function as partitions. Over the first electrode layers, a spacer654 a, a spacer 654 b, a spacer 654 c, and a spacer 654 d are formed.Similarly, over the insulators (insulating layers), a spacer 657 a, aspacer 657 b, a spacer 657 c, and a spacer 657 d are formed. FIG. 32shows an example in which the spacer 654 a, the spacer 654 b, the spacer654 c, the spacer 654 d, the spacer 657 a, the spacer 657 b, the spacer657 c, and the spacer 657 d are formed of the same material and by thesame step after forming the insulator 653 a, the insulator 653 b, theinsulator 653 c, and the insulator 653 d.

The spacer 654 a to the spacer 654 d, the spacer 657 a and the spacer657 b are formed by forming a layer with high planarity by a coatingmethod, and then patterning the layer by dry etching, thereby a heightfrom the substrate is equivalent, each spacer has a columnar shape andan upper surface connected to the mask has planarity. When the mask issupported by such spacers which have an equal height and planar supportsurfaces, the support surface of the mask increases, therefore, the maskcan be further stable. End portions thereof have preferably a smoothshape having curvatures so that the insulator 653 a to the insulator 653d improve the coverage of an electroluminescent layer and a secondelectrode layer which are formed thereover. When the insulators andspacers are formed through different steps, each spacer can be formed infree shape with a different material and a different step. Therefore, aspacer which is fit to a layout of a pixel and a vapor deposition maskcan be provided. It is needless to say that there is an advantage inthat a step can be shortened and a material can be used efficiently whenthe spacers and the insulators (insulating layers) over the pixelelectrode layers are formed of the same material and by the same step.After forming the spacers and the insulators over the pixel electrodelayers with the same material and by the same step, another spacer canbe formed over the pixel electrode layer again when forming the spacerover the insulator.

The first electrode layer 652 a and the first electrode layer 652 d arepixels to display red color and provided so as to correspond to anopening of a mask 656. Then, a light emitting material for red color isformed over the first electrode layer 652 a and the first electrodelayer 652 d as an electroluminescent layer. On the other hand, the firstelectrode layer 652 b is a pixel to display green color and the firstelectrode layer 652 c is a pixel to display blue color, therefore, theyare provided so as to correspond to a shielding portion of the mask 656.The mask 656 is stably supported by the spacers formed over the firstelectrode layers and the insulator, therefore, such problem does notoccur that the mask becomes contact with the first electrode layer dueto twist, deflection and the like, thereby the first electrode layer hasa defect in shapes. Therefore, the first electrode layer does notgenerate a light emission defect and a display defect, thereby a displaydevice with high reliability and high imago quality can be manufactured.

When an electroluminescent layer is formed over the pixel electrodelayer 652 a, the spacer 654 a provided over the pixel electrode layer652 a is not shielded by the mask, therefore, there is a case where anelectroluminescent layer is formed over the surface or periphery of thespacer 654 a. On the other hand, the insulator 653 a, the insulator 653b, the spacer 657 a, and the spacer 657 b are almost shield by the mask656, therefore, a place where an electroluminescent layer is formed isonly at the periphery close to an opening of the mask 656. In thisembodiment mode, when a plurality of spacers are provided such as thespacer 657 a formed over the insulator 653 a and the spacer 654 a formedover the pixel electrode layer 652 a, in vapor deposition of anelectroluminescent layer, the spacer 657 a connected to the mask 656 andthe spacer 654 a not connected to the mask 656 exist.

Further, in the case where light emitting materials for each color areselectively formed with one mask 656, after forming anelectroluminescent layer over the first electrode layer 652 a and thefirst electrode layer 652 d, the mask 656 is moved in a direction of anarrow 655 so that the electroluminescent layer can be formed over eachfirst electrode layer.

Subsequently, the second electrode layer 189 formed of a conductive filmis provided over the electroluminescent layer 188. As the secondelectrode layer 189, a material having a low work function (Al, Ag, Li,Ca, or an alloy or compound thereof, MgAg, MgIn, AlLi, CaF₂ or CaN) maybe used. In this manner, a light emitting element 190 formed of thefirst electrode layer 185, the electroluminescent layer 188, and thesecond electrode layer 189 is formed.

In the display device of this embodiment mode shown in FIG. 1, lightemitted from the light emitting element 190 is emitted from the firstelectrode layer 185 side through it in a direction of an arrow in FIG.1.

It is effective to provide a passivation film 191 so as to cover thesecond electrode layer 189. The passivation film 191 is formed of aninsulating film containing silicon nitride, silicon oxide, siliconoxynitride (SiON), silicon nitride oxide (SiNO), aluminum nitride (AlN),aluminum oxynitride (AlON), aluminum nitride oxide (AlNO) in whichnitrogen content is more than oxygen content, aluminum oxide,diamond-like carbon (DLC), or a nitrogen-containing carbon film (CN),and either a single layer of the insulating film or stacked layersthereof can be used. Moreover, a siloxane resin material may be used aswell.

At this time, it is preferable to use a film with favorable coverage asa passivation film, for which a carbon film, particularly a DLC film iseffectively used. A DLC film can be deposited in the temperature rangefrom a room temperature to 100° C., therefore, it can be easily formedabove an electroluminescent layer 119 with low heat resistance. A DLCfilm can be formed by a plasma CVD method-(typically an RF plasma CVDmethod, a microwave CVD method, an electron cyclotron resonance (ECR)CVD method, a thermal filament CVD method and the like), a combustionmethod, a sputtering method, an ion beam vapor deposition method, alaser vapor deposition method and the like. As a reaction gas used fordeposition, a hydrogen gas and a carbon hydride based gas (for example,CH₄, C₂H₂, C₆H₆ and the like) are used to be ionized by glow dischargeand the film is deposited by accelerating the ions to impact against acathode to which a negative self bias is applied. Further, a CN film maybe formed using a C₂H₄ gas and a N₂ gas as a reaction gas. A DLC filmhas a high blocking effect against oxygen, thereby oxidization of theelectroluminescent layer 188 can be suppressed. Therefore, a problemsuch that the electroluminescent layer 188 is oxidized while performinga subsequent sealing step can be prevented.

FIG. 18 shows a top plan view of a pixel region of a display devicemanufactured in this embodiment mode. In FIG. 18, the pixel 2702includes a TFT 501, a TFT 502, a capacitor 504, the first electrodelayer 185, a gate wiring layer 506, a source and drain wiring layer 505,and a power source line 507. The display device in FIG. 18 is a diagramin which the first electrode layer 185 is formed.

Subsequently, FIG. 30 shows a display device in which the insulator 186which cover the periphery of the ad portion of the first electrode layer185 and functions as a partition, the spacer 199, and the spacer 198 areformed. In FIG. 30, a plurality of the spacers 199 are provided over thefirst electrode layer and a plurality of spacers 198 are provided overthe insulator 186. The spacer 198 formed over the insulator 186 ispreferably formed in a region in which a thin film transistor is notformed under the insulator 186, since a defect such as an electrostaticdischarge does not easily occur. Further, instead of the spacer 198 overthe insulator, a mask in which a depression portion is formed in a placecorresponding to the spacer 198 may be used. The spacer may be one or aplurality of numbers, and in the case of providing a plurality ofspaces, they are not required to have the same shape. The mask used in astep of forming an electroluminescent layer is supported by the spacer,therefore, damage is not caused by contact with the first electrodelayer due to twist and deflection.

In this manner, by firmly fixing a sealing substrate 195 and thesubstrate 100 over which the light emitting element 190 is formed with asealing material 192, the light emitting element is sealed (see FIG. 1).In the display device of the invention, the sealing material 192 and theinsulator 186 are formed apart so as not to contact each other. In thismanner, when the scaling material and the insulator 186 are formed apartfrom each other, even when an insulating material using an organicmaterial having high moisture absorbing property is used for theinsulator 186, moisture does not easily enter so that deterioration ofthe light emitting element can be prevented to improve the reliabilityof the display device. As the sealing material 192, it is typicallypreferable to use a visible light curable resin, an ultraviolet curableresin, or a heat curable resin. For example, an epoxy resin can be usedsuch as a bisphenol-A liquid resin, a bisphenol-A solid resin, abromine-containing epoxy resin, a bisphenol-F resin, a bisphenol-ADresin, a phenol resin, a cresol resin, a novolac resin, a cycloaliphaticepoxy resin, an Epi-Bis type epoxy resin, a glycidyl ester resin, aglycidyl amine resin, a heterocyclic epoxy resin, and a modified epoxyresin. Note that a region surrounded by a sealing material may be filledwith a filling material 193, and may be sealed with nitrogen and thelike by sealing in a nitrogen atmosphere. This embodiment mode is abottom emission type, therefore, the filling material 193 is notrequired to have a light-transmitting property. However, in the case ofa structure extracting light through the filling material 193, thefilling material 193 is required to have a light-transmitting property.Typically, a visible light curable, ultraviolet curable, or heat curableepoxy resin may be used. By the aforementioned steps, a display devicehaving a display function using a light emitting element of thisembodiment mode is completed. Further, the display device may be filledwith the filling material by dropping a filling material in a liquidstate.

A dropping injection method adopting a dispenser method is describedwith reference to FIG. 19. The dropping injection method of FIG. 19includes a control device 40, an image pickup means 42, a head 43, afilling material 33, a marker 35, a marker 45, a barrier layer 34, ascaling material 32, a TFT substrate 30, and a counter substrate 20. Thefilling material 33 is dropped once or a plurality of times from thehead 43 in a closed loop formed by the sealing material 32. In the casewhere the material of the filling material has high viscosity, thefilling material is continuously discharged and attached to a formingregion without a break. On the other hand, in the case where thematerial of the filling material has low viscosity, the filling materialis intermittently discharged and dropped as shown in FIG. 19. At thistime, the barrier layer 34 may be provided to prevent that the sealingmaterial 32 reacts with the filling material 33. Subsequently, thesubstrates are attached to each other in vacuum and then ultravioletcuring is performed to be a state filled with the filling material. As afilling agent, a substance having a moisture absorbing property such asa drying agent may be used to obtain a further moisture absorbingeffect, thereby deterioration of the element can be prevented.

A drying agent is set in an EL display panel to prevent deterioration ofan element by moisture. In this embodiment mode, a drying agent is setin a depression portion formed in the sealing substrate so as tosurround the pixel region to form a structure which does not hinder athin design. Further, a drying agent is also formed in a regioncorresponding to a gate wiring layer so as to secure a wide moistureabsorbing area, thereby a moisture absorbing effect is high. Further, adrying agent is formed over a gate wiring layer which does not emitlight directly, therefore, light extraction efficiency is not decreasedeither.

Note that in this embodiment mode, the case where a light emittingelement is sealed with a glass substrate is shown, however, sealingtreatment is treatment for protecting a light emitting element frommoisture, and any one of a method for mechanically sealing the lightemitting element with a cover material, a method for sealing the lightemitting element with a heat curable resin or an ultraviolet curableresin, or a method for sealing the light emitting element with a thinfilm having a high barrier property such as a metal oxide, a nitride,and the like may be used. As the cover material, glass, ceramics,plastic, or metal can be used, however, a material is required to have alight-transmitting property in the case where light is emitted to thecover material side. Further, the cover material and the substrate overwhich the light emitting element is formed are attached using a sealingmaterial such as a heat curable resin or an ultraviolet curable resin,and the resin is cured by heat treatment or ultraviolet irradiationtreatment, thereby a sealed space is formed. It is also effective toprovide a moisture absorbing material typified by barium oxide in thissealed space. This moisture absorbing material may be provided incontact with the sealing material, or provided over or on the peripheryof the partition so as not to prevent the light from the light emittingelement. Furthermore, the space formed between the cover material andthe substrate over which the light emitting element is formed can befilled with a heat curable resin or an ultraviolet curable resin. Inthis case, it is effective to add an absorbing material typified bybarium oxide into the heat curable resin or the ultraviolet curableresin.

In this embodiment mode, an FPC 194 is connected to a terminal electrodelayer 178 through an anisotropic conductive layer 196 in an externalterminal connecting region 202 to form a structure electricallyconnected to external. Further, as shown in FIG. 1(A) which is a topplan view of a display device, a display device manufactured in thisembodiment mode includes a peripheral driver circuit region 207 a, and aperipheral driver circuit region 207 b each including a scan line drivercircuit as well as a peripheral driver circuit region 204 including asignal line driver circuit.

The aforementioned circuit is formed in this embodiment mode, howeverthe invention is not limited thereto. An IC chip may be mounted by theaforementioned COG method or TAB method as the peripheral drivercircuit. Further, each of the gate line driver circuit and the sourceline driver circuit may be in a plurality of numbers or a single number.

Moreover, in the display device of the invention, a driving method foran image display is not particularly limited, and for example, a dotsequential driving method, a line sequential driving method, an areasequential driving method and the like may be used. Typically, the linesequence driving method may be used, and a time division gray scaledriving method and an area gray scale driving method may beappropriately used as well. Further, a video signal inputted to thesource line of the display device may be an analog signal or a digitalsignal. The driver circuit and the like may be appropriately designed inaccordance with the video signal.

Further, a display device in which a video signal is digital includesthe one in which a constant voltage (CV) video signal is inputted to apixel or the one in which a constant current (CC) video signal isinputted to a pixel. A display device in which a video signal is theconstant voltage (CV) includes the one in which a constant voltage isapplied to a light emitting element (CVCV) and the one in which aconstant current is applied to a light emitting element (CVCC). Further,a display device in which a video signal is the constant current (CC)includes the one in which a constant voltage is applied to a lightemitting element (CCCV) and the one in which a constant current isapplied to a light emitting element (CCCC).

According to the invention, a display device with high reliability canbe manufactured by simplified steps. Therefore, a display device withhigh resolution and high image quality can be manufactured at low costwith high yield.

Embodiment Mode 2

An embodiment mode of the invention is described with reference to FIGS.7 to 9. This embodiment mode shows an example in which a secondinterlayer insulating layer is not formed in the display devicemanufactured in accordance with Embodiment Mode 1. Therefore, repetitivedescription on the same portion or a portion having a similar functionis omitted.

As shown in Embodiment Mode 1, the thin film transistor 173, the thinfilm transistor 174, thin film transistor 175, the thin film transistor176, and the conductive layer 177 are formed over the substrate 100, andthe insulating film 168 and the insulating film 168 are formed. A sourceelectrode layer or drain electrode layer connected to a source region ordrain region of a semiconductor layer is formed over each thin filmtransistor. A first electrode layer 395 in contact with the sourceelectrode layer or drain electrode layer 172 b in the thin filmtransistor 176 formed in the pixel region 206 is formed (see FIG. 7(A)).

The first electrode layer 395 functions as a pixel electrode and may beformed with the same material and by the same step as the firstelectrode layer 185 in Embodiment Mode 1. In this embodiment mode, thefirst electrode layer 395 is formed using ITSO which is a transparentconductive film and patterning it in order to extract light through thefirst electrode layer similarly to Embodiment Mode 1.

The insulator 186 is formed to cover an end portion of the firstelectrode layer 395 and the thin film transistor, and the spacer 199 isformed over the pixel electrode layer. After forming the insulator 186,the spacer 198 is formed over the insulator 186 (see FIG. 7(B)). Acrylicis used for the insulator 186 and the spacer 199 in this embodimentmode. In this embodiment mode, the spacer 198 has a columnar shape ofwhich an upper surface has higher planarity. A mask for forming anelectroluminescent layer is supported by the spacer 198 and the spacer199, thereby damage of the pixel electrode layer is not caused by themask. Therefore, a display device with high image quality and highreliability can be manufactured. Further, as in this embodiment mode,when a projection portion is formed by the spacer 198 to form astructure in which the sealing substrate 195 is supported by theprojection portion, a space between the element substrate and thesealing substrate can be controlled to be uniform. When the space isuniform, a display defect such that light emitted from a light emittingelement is interfered is not generated so that good and high imagequality display can be performed.

The electroluminescent layer 188 is formed over the first electrodelayer and the second electrode layer 189 is stacked thereover to formthe light emitting element 190. The second electrode layer 189 iselectrically connected to the wiring layer 156 in the connecting region205 while the terminal electrode layer 178 is connected to the FPC 194through the anisotropic conductive layer 196 in the external terminalconnecting region 202. The passivation film 191 is formed so as to coverthe second electrode layer 189. The substrate 100 is attached to thesealing substrate 195 with the sealing material 192, thereby inside thedisplay device is filled with the filling material 193 (see FIG. 8). Inthe display device of the invention, the sealing material 192 and theinsulator 186 are formed apart so as not to be in contact with eachother. In this manner, when the sealing material and the insulator 186are formed apart from each other, even when an insulating material usingan organic material having a high moisture absorbing property is usedfor the insulator 186, moisture does not easily enter so thatdeterioration of the light emitting element can be prevented to improvethe reliability of the display device.

Further, in a display device in FIG. 9, the first electrode layer 395can be selectively formed over the insulating film 168 before formingthe source electrode layer or drain electrode layer 172 b connected tothe thin film transistor 176. In this case, according to this embodimentmode, a connecting structure of the first electrode layer 395 and thesource electrode layer or drain electrode layer 172 b is a structure inwhich the source electrode layer or drain electrode layer 172 b isstacked over the first electrode layer 395. When the first electrodelayer 395 is formed before the source electrode layer or drain electrodelayer 172 b, a plane forming region can be formed. Accordingly, suchadvantages can be provided that good coverage and film deposition can beachieved with high planarity and polish treatment such as CMP can besufficiently performed.

According to the invention, a display device with high reliability canbe manufactured by simplified steps. Therefore, a display device withhigh resolution and high image quality can be manufactured at low costwith high yield.

Embodiment Mode 3

An embodiment mode of the invention is described with reference to FIG.10. This embodiment mode shows an example in which a gate electrodelayer structure of a thin film transistor is different in the displaydevice manufactured in accordance with Embodiment Mode 1. Therefore,repetitive description on the same portion or a portion having a similarfunction is omitted.

Each of FIGS. 10(A) to (C) is a display device in a manufacturing step,and corresponds to the display device of Embodiment Mode 1 shown in FIG.4(B).

In FIG. 10(A), a thin film transistor 273 and a thin film transistor 274are provided in a peripheral driver circuit region 214, a conductivelayer 277 is provided in a connecting region, and a thin film transistor275 and a thin film transistor 276 are provided in a pixel region 216. Agate electrode layer of the thin film transistor in FIG. 10(A) is formedof stacked layers of two conductive films and an upper layer of the gateelectrode layer is patterned to have a thinner width than a lower layerof the gate electrode layer. Although the lower layer of the gateelectrode layer has a tapered shape, the upper layer of the gateelectrode layer does not have a tapered shape. In this manner, a gateelectrode layer may have a tapered shape or a shape of which side angleis almost perpendicular, a so-called shape without a tapered shape.

In FIG. 10(B), a thin film transistor 373 and a thin film transistor 374are provided in the peripheral driver circuit region 214, a conductivelayer 377 is provided in the connecting region, and a thin filmtransistor 375 and a thin film transistor 376 are provided in the pixelregion 216. Although a gate electrode layer of the thin film transistorin FIG. 10(B) is also formed of stacked layers of two conductive films,each of an upper layer of the gate electrode layer and a lower layer ofthe gate electrode layer has a continuous tapered shape.

In FIG. 10(C), a thin film transistor 473 and a thin film transistor 474are provided in the peripheral driver circuit region 214, a conductivelayer 477 is provided in the connecting region, and a thin filmtransistor 475 and a thin film transistor 476 are provided in the pixelregion 216. A gate electrode layer of the thin film transistor in FIG.10(C) has a single-layer structure and has a tapered shape. In thismanner, the gate electrode layer may have a single-layer structure.

As set forth above, the gate electrode layer may have various structuresin accordance with the structure and shape thereof. Therefore, a displaydevice manufactured thereby also shows various structures. In the casewhere in an impurity region of a semiconductor layer is formed in aself-aligned manner with the gate electrode layer as a mask, a structureand concentration distribution of the impurity region are changed inaccordance with the structure of the gate electrode layer. A thin filmtransistor having a desired function can be manufactured by designing inconsideration of the aforementioned aspects.

This embodiment mode can be implemented in combination with each ofEmbodiment Modes 1 and 2.

Embodiment Mode 4

A display device having a light emitting element can be formed byadopting the invention, and light emitted from the light emittingelement is emitted to any one of a bottom side, top side, or dual sides.In this embodiment mode, examples of a dual emission type and a topemission type are described with reference to FIGS. 11 and 12.

A display device shown in FIG. 12 includes an element substrate 1300, athin film transistor 1355, a thin film transistor 1365, a thin filmtransistor 1375, a first electrode layer 1317, an electroluminescentlayer 1319, a second electrode layer 1320, a transparent conductive film1321, a filling material 1322, a sealing material 1325, a gateinsulating layer 1310, an insulating film 1311, an insulating film 1312,an insulating film 1313, an insulating film 1309, an insulator(insulating layer) 1314, a sealing substrate 1323, a wiring layer 1380,a terminal electrode layer 1381, an anisotropic conductive layer 1382,an FPC 1383, a spacer 1330, a spacer 1399 a, and a spacer 1399 b. Asshown in FIG. 12, a plurality of the spacers 1399 a and the spacers 1399b having different shapes may be formed over the insulator. The displaydevice has a separating region 221, an external terminal connectingregion 222, a wiring region 223, a peripheral driver circuit region 224,and a pixel region 226. The filling material 1322 can be formed using acomposition in liquid form by a dropping method as a dropping method ofFIG. 19. The element substrate 1300 over which the filling material isformed by the dropping method and the sealing substrate 1323 areattached to seal a light emitting display device.

The display device shown in FIG. 12 is a dual emission type and has astructure in which light is emitted in directions of arrows from theelement substrate 1300 side and the sealing substrate 1323 side as well.Note that in this embodiment mode, the first electrode layer 1317 isformed by depositing a transparent conductive film and etching it into adesired shape. A transparent conductive film can be used as the firstelectrode layer 1317. As the first electrode layer 1317, a titaniumnitride film or a titanium film may be used other than theaforementioned transparent conductive film. In this case, afterdepositing a transparent conductive film, a titanium nitride film or atitanium film is formed with a thickness enough to transmit light(preferably about 5 to 30 nm). In this embodiment mode, ITSO is used asthe first electrode layer 1317.

Subsequently, the second electrode layer 1320 formed of a conductivefilm is provided over the electroluminescent layer 1319. As the secondelectrode layer 1320, a material having a low work function (Al, Ag, Li,Ca, or an alloy or compound thereof, MgAg, MgIn, AlLi, CaF₂ or CaN) maybe used. In the display device of FIG. 6, stacked layers are used inwhich a metal thin film having a thin film thickness (MgAg:filmthickness of 10 nm) is used for the second electrode layer 1320 and ITSOwith a thickness of 100 nm is used for the transparent conductive film1321 so as to transmit light. As the transparent conductive film 1321, asimilar film to the aforementioned first electrode layer 1317 can beused.

The display device in FIG. 11 is a one-side light emission type and hasa structure in which light is emitted to the top side in a direction ofan arrow. The display device shown in FIG. 11 includes an elementsubstrate 1600, a thin film transistor 1655, a thin film transistor1665, a thin film transistor 1675, a metal layer 1624 havingreflectivity, a first electrode layer 1617, an electroluminescent layer1619, a second electrode layer 1620, a transparent conductive film 1621,a filling material 1622, a sealing material 1625, a gate insulatinglayer 1610, an insulating film 1611, an insulating film 1612, aninsulating film 1613, an insulating film 1609, an insulator (insulatinglayer) 1614, a sealing substrate 1623, a wiring layer 1680, a terminalelectrode layer 1681, an anisotropic conductive layer 1682, an FPC 1683,a spacer 1630, and spacers 1699. In the display device in FIG. 11, aninsulating layer stacked over the terminal electrode layer 1681 isetched and removed. In this manner, when a structure in which aninsulating layer having moisture permeability is not provided on theperiphery of the terminal electrode layer, the reliability can befurther improved. Moreover, the display device includes a separatingregion 231, an external terminal connecting region 232, a wiring region233, a peripheral driver circuit region 234, and a pixel region 236. Inthis case, in the aforementioned dual emission type display device shownin FIG. 12, the metal layer 1624 having reflectivity is formed under thefirst electrode layer 1317. The first electrode layer 1617 which is atransparent conductive film functioning as an anode is formed over themetal layer 1624 having reflectivity. Since the metal layer 1624 mayhave reflectivity, Ta, W, Ti, Mo, Al, Cu, and the like may be used. Itis preferable to use a substance having high reflectivity in a visiblelight region. In this embodiment mode, a TIN film is used.

The second electrode layer 1620 formed of a conductive film is providedover the electroluminescent layer 1619. As the second electrode layer1620 which functions as a cathode, a material having a low work function(Al, Ag, Li, Ca, or an alloy or compound thereof, MgAg, MgIn, AlLi, CaF₂or CaN) may be used. In this embodiment mode, stacked layers are used inwhich a metal thin film having a thin film thickness (MgAg:filmthickness of 10 nm) is used for the second electrode layer 1620 and ITSOwith a thickness of 110 nm is used for the transparent conductive film1621 so as to transmit light.

A mode of a light emitting element applicable to this embodiment mode isshown in FIG. 13. A light emitting element has a structure with anelectroluminescent layer 860 interposed between a first electrode layer870 and a second electrode layer 850. A material for the first electrodelayer and the second electrode layer is required to be selected inconsideration of a work function, and either of the first electrodelayer or the second electrode layer may be an anode or a cathodedepending on a pixel structure. In this embodiment mode, in the casewhere the polarity of a driving TFT is a p-channel type, the firstelectrode layer may be an anode and the second electrode layer may be acathode. Further, since the polarity of the driving TFT is an n-channeltype, it is preferable that the first electrode layer be a cathode andthe second electrode layer be an anode.

FIGS. 13(A) and 13(B) show the case where the first electrode layer 870is an anode and the second electrode layer 850 is a cathode. It ispreferable that the electroluminescent layer 860 be formed by stackingan HIL (hole injecting layer) HTL (hole transporting layer) 804, an EML(light emitting layer) 803, an ETL (electron transporting layer) EIL(electron injecting layer) 802, and the second electrode layer 850 inthis order from the first electrode layer 870 side. FIG. 13(A) shows astructure in which light is emitted from the first electrode layer 870,and the first electrode layer 870 is formed of an electrode layer 805formed of an oxide conductive material having a light-transmittingproperty, and the second electrode layer is formed of an electrode layer801 containing an alkali metal such as LiF and MgAg or alkaline earthmetal and an electrode layer 800 formed of a metal material such asaluminum from the electroluminescent layer 860 side. FIG. 13(B) shows astructure in which light is emitted from the second electrode layer 850,and the first electrode layer is formed of an electrode layer 807 formedof a metal such as aluminum and titanium, or a metal material containingthe aforementioned metal and nitrogen at a concentration equal to orlower than the stoichiometric composition ratio, and a second electrodelayer 806 formed of an oxide conductive material containing siliconoxide at a concentration of 1 to 15 atomic %. The second electrodelayer, the second electrode layer is formed of an electrode layer 801containing an alkaline metal such as LiF and MgAg or an alkaline earthmetal and an electrode layer 800 formed of a metal material such asaluminum from the electroluminescent layer 860 side. Both of the layersare formed with a thickness of 100 nm or less to be a state that lightcan be transmitted, therefore, light can be emitted from the secondelectrode layer 850.

FIGS. 13(C) and (D) show the case where the first electrode layer 870 isa cathode and the second electrode layer 850 is an anode. It ispreferable that the electroluminescent layer 860 be formed by stackingthe EIL (electron injecting layer) ETL (electron transporting layer)802, the EML (light emitting layer) 803, the HTL (hole transportinglayer) HIL (hole injecting layer) 804, and the second electrode layer850 as an anode in this order from a cathode side. FIG. 13(C) shows astructure in which light is emitted from the first electrode layer 870,and the first electrode layer 870 is formed of the electrode layer 801containing an alkaline metal such as LiF and MgAg or an alkaline earthmetal, and the electrode layer 800 formed of a metal material such asaluminum from the electroluminescent layer 860 side. Both of the layersare formed with a thickness of 100 nm or less to be capable oftransmitting light, therefore, light can be emitted from the firstelectrode layer 870. The second electrode layer is formed of the secondelectrode layer 806 formed of an oxide conductive material containingsilicon oxide at a concentration of 1 to 15 atomic %, and the electrodelayer 807 formed of a metal such as aluminum and titanium, or a metalmaterial containing the aforementioned metal and nitrogen at aconcentration equal to or lower than the stoichiometric compositionratio from the electroluminescent layer 860 side. FIG. 13(D) shows astructure in which light is emitted from the second electrode layer 850.The first electrode layer 870 is formed of the electrode layer 801containing an alkaline metal such as LiF and MgAg or an alkaline earthmetal and the electrode layer 800 formed of a metal material such asaluminum from the electroluminescent layer 860 side, with an enough filmthickness to reflect light emitted from the electroluminescent layer860. The second electrode layer 850 is formed of the electrode layer 805formed of an oxide conductive material having a light-transmittingproperty. Note that the electroluminescent layer can have a single-layerstructure or a mixed-layer structure other than the stacked-layerstructure.

Further, a material which exhibits light emission of each of red (R),green (G), and blue (B) is selectively formed by a vapor depositionmethod using a vapor deposition mask and the like as anelectroluminescent layer. The material which exhibits light emission ofred (R), green (G), and blue (B) can be formed by a droplet dischargemethod similarly to a color filter (a low molecular or high molecularweight material and the like). This method is preferable since RGB canbe separately deposited without using a mask.

Further, in the case of using ITO or ITSO having a light-transmittingproperty as the second electrode layer in the case of the top emissiontype, BzOs-Li in which Li is added to benzoxazole derivatives (BzOs) andthe like can be used. Further, for example, Alq₃ doped with dopant (DCMor the like in the case of R, and DMQD or the like in the case of G)corresponding to each emission color of R, G, and B may be used for anEML.

Note that the electroluminescent layer is not limited to theaforementioned materials. For example, it can be formed byco-evaporation of an oxide such as molybdenum oxide (MoO_(x): x=2 to 3)or the like and α-NPD or rubrene instead of using CuPc or PEDOT, therebya hole injecting property can be improved. Further, an organic material(containing low molecular weight or high molecular weight) or acomposite material of an organic material and an inorganic material canbe used as the electroluminescent layer material. Hereinafter, amaterial for forming a light emitting element is described in details.

Among charge injecting/transporting substances, as a substance having aparticularly high electron transporting property, for example, there isa metal complex or the like having a quinoline skeleton or abenzoquinoline skeleton such as tris(8-quinolinolato) aluminum(abbreviated: Alq₃), tris(5-methyl-8-quinolinolate) aluminum(abbreviated: Almq₃), bis(10-hydroxybenzo[h]-quinolinato) beryllium(abbreviated: BeBq₂), orbis(2-methyl-8-quinolinolato)-4-phenylphenolato-aluminum (abbreviated:BAlq). Moreover, as a substance having a high hole transportingproperty, for example, there are aromatic amine based (that is, having abenzene ring-nitrogen bond) compounds such as4,4′-bis[N-(1-naphthyl)-N-phenyl-amino]-biphenyl (abbreviated: α-NPD),4,4′-bis[N-(3-methylphenyl)-N-phenyl-amino]-biphenyl (abbreviated: TPD),4,4′,4″-tris(N,N-diphenyl-amino)-triphenylamine (abbreviated: TDATA),and 4,4′,4″-tris[N-(3-methylphenyl)-N-phenyl-amino]-triphenylamine(abbreviated: MTDATA).

Further, among charge injecting/transporting substances, as a substancehaving a particularly high electron injecting property, there is acompound of an alkali metal or an alkali earth metal such as lithiumfluoride (LiF), cesium fluoride (CsF), or calcium fluoride (CaF₂).Besides, a mixture of a substance having a high electron transportingproperty such as Alq₃ and an alkali earth metal such as magnesium (Mg)may be used as well.

Among charge injecting/transporting substances, as a substance having ahigh hole injecting property, for example, there is a metal oxide suchas molybdenum oxide (MoO_(x)), vanadium oxide (VO_(x)), ruthenium oxide(RuO_(x)), tungsten oxide (WO_(x)), or manganese oxide (MnO_(x)).Besides, a phthalocyanine compound such as phthalocyanine (abbreviated:H₂Pe) or copper phthalocyanine (CuPe) may be used.

A light emitting layer may have a structure in which each of lightemitting layers having different emission wavelength bands isrespectively formed in each pixel for performing color display.Typically, light emitting layers corresponding to the respective colorsof R (red), G (green), and B (blue) are formed. In this case, by forminga structure where a filter which transmits light having each emissionwavelength band at the light emission side of the pixel is provided,color purity can be improved and a pixel portion can be prevented frombeing a mirror surface (reflection). By providing the filter, a circularpolarizing plate or the like that is conventionally required can beomitted, therefore, loss of light emitted from the light emitting layercan be prevented. Moreover, color changes which occur in the case wherethe pixel portion (display screen) is seen obliquely can be reduced.

There are various materials in light emitting materials. As a lowmolecular weight organic light emitting material,4-dicyanomethylene-2-methyl-6-[2-(1,1,7,7-tetramethyl-9-juiolidyl)-ethenyl]-4H-pyran(abbreviated: DCJT),4-dicyanomethylene-2-t-butyl-6-[2-(1,1,7,7-tetramnethyljulolidine-9-yl)ethenyl]-4H-pyran(abbreviated: DCJTB), periflanthene,2,5-dicyano-1,4-bis[2-(10-methoxy-1,1,7,7-tetramethyljulolidine-9-yl)-ethenyl]benzene,N,N′-dimethyl quinacridone (abbreviated: DMQd), coumarin 6, coumarin545T, tris(8-quinolinolato)aluminum (abbreviated: Alq₃), 9,9′-biantrile,9,10-diphenylanthracene (abbreviated: DPA),9,10-bis(2-naphtyl)anthracene (abbreviated: DNA), or the like can beused. Further, other substances may be used as well.

On the other hand, a high molecular weight organic light emittingmaterial has higher physical strength compared to a low molecular weightorganic light emitting material, and an element has high durability.Moreover, a film deposition is possible by coating, thereby an elementcan be comparatively easily manufactured. A structure of a lightemitting element using a high molecular weight organic light emittingmaterial is basically the same as that of a light emitting element usinga low molecular weight organic light emitting material. The structure issuch that a cathode, an organic light emitting layer, and an anode areformed in this order. However, it is difficult to form a stacked-layerstructure as in the case of using a low molecular weight organic lightemitting material when a light emitting layer is formed using a highmolecular weight organic light emitting material, and in many cases, atwo-layer structure is applied. Specifically, a structure is such that acathode, a light emitting layer, a hole transporting layer, and an anodeare formed in this order.

Emission color is determined by a material for forming a light emittinglayer, thereby a light emitting element which exhibits desired lightemission can be formed by selecting the material. As a high molecularweight electroluminescent material which can be used for forming a lightemitting layer, there is a polyparaphenylene vinylene based material, apolyparaphenylene based material, polythiophene based material, or apolyfluorene based material.

As the polyparaphenylene vinylene based material, there are a derivativeof poly(paraphenylene vinylene) [PPV], poly(2,5-dialkoxy-1,4-phenylenevinylene) [RO-PPV], poly(2-(2′-ethyl-hexoxy)-5-methoxy-1,4-phenylenevinylene) [MEH-PPV], poly(2-(dialkoxyphenyl)-1,4-phenylenevinylene)[ROPh-PPV], and the like. As the polyparaphenylene based material, thereare a derivative of polyparaphenylene [PPP],poly(2,5-dialkoxy-1,4-phenylene) [RO-PPP],poly(2,5-dihexoxy-1,4-phenylene), and the like. As the polythiophenebased material, there are a derivative of polythiophene [PT],poly(3-allylthiophene) [PAT], poly(3-hexylthiophene) [PHT],poly(3-cyclohexylthiophene) [PCHT], poly(3-cyclohexyl-4-methylthiophene)[PCHMT], poly(3,4-dicyclohexylthiophene) [PDCHT],poly[3-(4-octylphenyl)-thiophene] [POPT], poly[3-(4-octylphenyl)-2,2bithiophene] [PTOPT], and the like. As the polyfluorene based material,there are a derivative of polyfluorene [PF], poly(9,9-dialkylfluorene)[PDAF], poly(9,9-dioctylfluorene) [PDOF], and the like.

Note that a hole injecting property from the anode can be improved whena high molecular weight organic light emitting material having a holetransporting property is interposed between the anode and a highmolecular weight organic light emitting material having a light emittingproperty. In general, the high molecular weight organic light emittingmaterial having a hole transporting property and an acceptor materialdissolved together in water are applied by a spin coating method and thelike. Further, since the high molecular weight organic light emittingmaterial having a hole transporting property does not dissolve inorganic solvent, the stacked layers of the material and theaforementioned organic light emitting material having a light emittingproperty can be used. As the high molecular weight organic lightemitting material having a hole transporting property, there are amixture of PEDOT and camphorsulfonic acid (CSA) as an acceptor material,a mixture of polyaniline [PANI] and polystyrenesulfonic acid [PSS] as anacceptor material, and the like.

Moreover, the light emitting layer can have a structure to exhibitmonochromatic emission or white emission. In the case of using a whiteemission material, color display can be realized as a structure in whicha filter (colored layer) which transmits light with a specifiedwavelength is provided at the light emission side of the pixel.

To form a light emitting layer which exhibits white emission, forexample, Alq₃, Alq₃ partly doped with Nile red as a red light emittingpigment, Alq₃, p-EtTAZ, and TPD (aromatic diamine) are stackedsequentially by a vapor deposition method so that white color can beobtained. Further, in the case where an EL is formed by a coating methodusing spin coating, the material is preferably baked by vacuum heatingafter being applied. For example, poly(ethylenedioxythiophene)/poly(styrene sulfonic acid) solution (PEDOT/PSS) whichfunctions as a hole injecting layer may be applied onto a whole surfaceand baked, and thereafter, polyvinylcarbazole (PVK) solution doped withluminescent center pigments which function as a light emitting layer(1,1,4,4-tetraphenyl-1,3-butadiene (TPB),4-dicyanomethylene-2-methyl-6-(p-dimethylamino-styryl)-4H-pyran (DCM1),Nile red, coumarin 6, or the like) may be applied onto a whole surfaceand baked.

The light emitting layer can also be formed with a single layer, and a1,3,4-oxadiazole derivative (PBD) having an electron transportingproperty may be dispersed in polyvinylcarbazole (PVK) having a holetransporting property. Further, white emission can be obtained bydispersing PBD of 30 wt % as an electron transporting agent anddispersing an appropriate amount of four kinds of pigments (TPB,coumarin 6, DCM1, and Nile red). In addition to the light emittingelement which can provide white emission as described here, a lightemitting element which can provide red emission, green emission, or blueemission can be manufactured by appropriately selecting a material of alight emitting layer.

Moreover, besides the singlet excited light emitting material, a tripletexcited material containing a metal complex or the like may be used forthe light emitting layer. For example, among a red light emitting pixel,a green light emitting pixel, and a blue light emitting pixel, the redlight emitting pixel having comparatively short half-brightness lifetimeis formed with a triplet excited light emitting material and the othersare formed with singlet excited light emitting materials. The tripletexcited light emitting material has a characteristic in that it requireslower power consumption to obtain the same luminance because of highluminous efficiency. That is, in the case of applying the tripletexcited material to the red light emitting pixel, the reliability can beimproved since the amount of current to flow to the light emittingelement can be small. To reduce power consumption, the red lightemitting pixel and the green light emitting pixel may be formed with thetriplet excited light emitting materials, and the blue light emittingpixel may be formed with a singlet excited light emitting material. Byforming a green light emitting element that has high visibility tohumans, with the triplet excited light emitting material, the powerconsumption can be reduced further.

As an example of the triplet excited light emitting substance, there isa material using a metal complex as a dopant, and a metal complexincluding platinum which is a the third transition series element as acentral metal, a metal complex including iridium as a central metal orthe like is known. The triplet excited light emitting material is notlimited to these compounds. A compound which has the aforementionedstructure and has an element belonging to groups 8 to 10 in the periodictable of elements as a central metal can be used.

Above mentioned materials for forming the light emitting layer are onlyexamples. The light emitting element can be formed by appropriatelystacking each functional layer such as a hole injecting/transportinglayer, a hole transporting layer, an electron injecting/transportinglayer, an electron transporting layer, a light emitting layer, anelectron blocking layer, and a hole blocking layer. Moreover, a mixedlayer or mixed junction in which each of the above layers is combinedmay be formed as well. The layer structure of the light emitting layeris changeable. Therefore, instead of providing a specific electroninjecting region or light emitting region, modifications of thestructure may be allowed without departing from the scope of theinvention, for example by providing an electrode layer for this purpose,or providing a dispersed light emitting material.

The light emitting element formed with the aforementioned materialsemits light with forward bias. A pixel of a display device formed usingthe light emitting element can be driven by either a simple matrixmethod or an active matrix method. In any case, although each pixelemits light by applying forward bias thereto at a specified timing, eachpixel is in a non-light emission state for a certain period. Thereliability of the light emitting element can be improved by applyingreverse bias thereto in the non-light emission period. The lightemitting element may be in deterioration in which light emissionintensity is decreased under a regular driving condition or may be in adeterioration mode in which apparent luminance is decreased due to theexpansion of a non-light emission region in the pixel. However, theprogress of deterioration can be delayed by AC driving to apply forwardbias and reverse bias so that the reliability of the light emittingdevice can be improved. Further, both digital drive and analog drive canbe applied.

Therefore, a color filter (colored layer) may be formed over the sealingsubstrate. The color filter (colored layer) can be formed by a vapordeposition method or a droplet discharge method. When using a colorfilter (colored layer), high definition display can be performed, sincea broad peak in an emission spectrum of each RGB can be corrected into asharp peak by the color filter (colored layer).

The case of forming materials which exhibit each light emission of RGBis described above. A full color display can be performed by forming amaterial which exhibits monochromatic emission and combining a colorfilter or a color conversion layer. The color filter (colored layer) orthe color conversion layer may be formed, for example, over a secondsubstrate (sealing substrate) and attached to a substrate.

It is needless to say that monochromatic emission display may beperformed. For example, an area color type display device may be formedby using monochromatic emission. An area color type is suitable for apassive matrix type display portion and can display mainly text orsymbols.

In the aforementioned structure, a material having a low work functioncan be used as the cathode. For example, Ca, Al, CaF, MgAg, AlLi, andthe like are desirable. The electroluminescent layer may be formed of asingle layer type, a stacked-layer type or a mixed type which does nothave an interface between layers. Further, the electroluminescent layermay be formed with a singlet material, a triplet material, combinedmaterial thereof or a charge injecting/transporting substance containingan organic compound or an inorganic compound, and a light emittingmaterial. The electroluminescent layer may include one or a plurality oflayers, selected, based on the number of molecules, from a low molecularweight organic compound, an intermediate molecular weight organiccompound (referred to an organic compound which does not have asubliming property and which has the number of molecules of 20 orshorter, or which has a molecular chain length of 10 μm or shorter), anda high molecular weight organic compound, and an inorganic compoundhaving an electron injecting/transporting property or a holeinjecting/transporting property can be combined with theelectroluminescent layer. The first electrode layer is formed of atransparent conductive film which transmits light. For example, ITO,ITSO, or a transparent conductive film in which zinc oxide (ZnO) of 2 to20% is mixed with indium oxide is used. Note that before forming thefirst electrode layer, plasma treatment in an oxygen atmosphere or heattreatment under vacuum atmosphere may be performed. A partition (alsoreferred to as a bank) is formed using a material containing silicon, anorganic material, and a compound material. Further, a porous film may beused as well. However, the partition is preferably formed using aphotosensitive material or non-photosensitive material such as acrylicor polyimide, since the edge of the partition has a shape of which aradius of curvature varies continuously so that a thin film of an upperlayer is formed without a break. This embodiment mode can be freelycombined with the aforementioned embodiment modes.

According to the invention, a display device with high reliability canbe manufactured through simplified steps. Therefore, a display devicewith high resolution and high image quality can be manufactured at lowcost with high yield.

This embodiment mode can be used in combination with any one ofEmbodiment Modes 1 to 3.

Embodiment Mode 5

Described with reference to FIG. 15 is a mode in which a protectivediode is provided for each of a scan line side input terminal portionand a signal line side input terminal portion. In FIG. 15, the TFT 501,the TFT 502, the capacitor 504, and a pixel electrode layer 503 areprovided in the pixel 2702. These TFTs have similar structures toEmbodiment Mode 1. A spacer 510 a and a spacer 510 b are provided overthe pixel electrode layer 503, and a spacer 511 a and a spacer 511 b areprovided over an insulator (not shown) covering the periphery of thepixel electrode layer 503. These spacers support a vapor deposition maskused for forming an electroluminescent layer over the pixel electrodelayer 503. Accordingly, these spacers can prevent the mask fromcontacting the pixel electrode layer 503 and thus causing damagethereto.

A protective diode 561 and a protective diode 562 are provided in thesignal line side input terminal portion. These protective diodes aremanufactured by similar steps to the TFT 501 and the TFT 502, and a gateand one of a drain and a source thereof are connected to each other tooperate as a diode. FIG. 14 shows an equivalent circuit diagram of a topplan view shown in FIG. 15.

The protective diode 561 includes a gate electrode layer, asemiconductor layer, and a wiring layer. The protective diode 562 alsohas a similar structure. A common potential line 554 and a commonpotential line 555 which are connected to these protective diodes areformed of the same layer as the gate electrode layer. Accordingly, acontact hole is required to be formed in an insulating layer so as to beelectrically connected to the wiring layer.

A contact hole in the insulating layer may be formed with a mask layerto perform an etching process. In this case, when adopting an etchingprocess of atmospheric pressure discharge, local electric dischargeprocess is possible, and a mask layer is not required to be formed overthe entire surface of the substrate.

A signal wiring layer is formed of the same layer as the source anddrain wiring layer 505 in the TFT 501 and has a structure that thesignal wiring layer connected thereto and the source or drain side areconnected to each other.

An input terminal portion on the scan signal line side also has asimilar structure. A protective diode 563 includes a gate electrodelayer, a semiconductor layer, and a wiring layer. A protective diode 564also has a similar structure. A common potential line 556 and a commonpotential line 557 which are connected to these protective diodes areformed of the same layer as the source and drain wiring layer. Theprotective diodes provided in an input stage can be formed at the sametime. Note that although the position in which the protective diode isinserted is not limited to this embodiment mode, it can be providedbetween a driver circuit and a pixel.

Embodiment Mode 6

With a display device formed in accordance with the invention, atelevision device can be completed. A display panel may be in any one ofmodes such as a case where only a pixel portion is formed as a structureshown in FIG. 16(A) and a scan line side driver circuit and a signalline side driver circuit are mounted by a TAB method as shown in FIG.17(B) or a case mounted by a COG method as shown in FIG. 17(A), a casewhere a TFT is formed with SAS as shown in FIG. 16(B), a pixel portionand a scan line side driver circuit are integrally formed over thesubstrate, and a signal line side driver circuit is mounted as a driverIC separately, a case where a pixel portion, a signal line side drivercircuit, and a scan line side driver circuit are integrally formed overthe substrate as shown in FIG. 16(C), and the like.

Other external circuit configurations include, a video signal amplifiercircuit for amplifying a video signal among signals received by a tuner,a video signal processing circuit for converting the outputted signaltherefrom into a color signal corresponding to each color of red, greenand blue, a control circuit for converting the video signal into inputspecification of a driver IC, and the like. The control circuit outputssignals to each of the scan line side and the signal line side. In thecase of digital driving, a configuration in which a signal dividercircuit is provided on the signal line side and an input digital signalis divided into m signals to be supplied may be used as well.

An audio signal among signals received by the tuner is transmitted to anaudio signal amplifier circuit, and an output thereof is supplied to aspeaker through an audio signal processing circuit A control circuitreceives data on receiving station (received frequency) and volumecontrol from an input portion, and transmits the signals to the tuner orthe audio signal processing circuit.

By incorporating a display module into a housing, a television device asshown in FIGS. 20(A) and (B) can be completed. A display panel to whichan FPC is attached as shown in FIG. 1 is also generally referred to asan EL display module. Accordingly, when using the EL display module asshown in FIG. 1, an EL television device can be completed. A maindisplay 2003 is formed by a display module and a speaker portion 2009,an operating switch and the like are provided as other accessoryequipment. In this manner, a television device can be completed inaccordance with the invention.

Further, a retardation plate or a polarizing plate may be used to blockthe reflection light of external incident light. Moreover, in the caseof a display device of the top emission type, an insulating layer to bea partition may be colored to be used as a black matrix. This partitioncan be formed by the droplet discharge method and the like, and a blackpigment resin, mixture of a carbon black or the like with a resinmaterial such as polyimide, or stacked layers thereof may be as well.The partition may be formed by discharging different materials onto thesame region a plurality of times by the droplet discharge method. As theretardation plate, a retardation plate, λ/4 plate and a λ/2 plate may beused to design for controlling light. As the structure, a TFT elementsubstrate, a light emitting element, a sealing substrate (sealingmember), the retardation plate, the retardation plate (the λ/4 plate andthe λ/2 plate), and a polarizing plate are sequentially stacked. Lightemitted from the light emitting element is emitted outside from thepolarizing plate side through them. The retardation plate and thepolarizing plate may be provided on a side through which light isemitted. In the case of a dual emission type display device which emitslight to both sides, the retardation plate and the polarizing plate canbe provided on both sides. In addition, an anti-reflection film may beprovided on the outer side of the polarizing plate. Therefore, highresolution and fine image can be displayed.

As shown in FIG. 20(A), a display panel 2002 using a display element isincorporated in a housing 2001 and a receiver 2005 is connected to acommunication network by wired or wireless connections through a modem2004 in addition to receive general TV broadcast so that one-way (from asender to a receiver) or two-way (between a sender and a receiver orbetween receivers) data communication can be carried out. The operationof the television device can be performed with a switch incorporated inthe housing or a separate remote control operation unit 2006, and thisremote control device may also be provided with a display portion 2007for displaying output data.

Further, a sub screen 2008 may also be formed by a second display panelto add a structure which displays channels, volume, and the like inaddition to the main screen 2003 in the television device. In thisstructure, the main screen 2003 may be formed by an EL display panelhaving an excellent viewing angle and the sub screen may be formed by aliquid crystal display panel capable of displaying at lower powerconsumption. Alternatively, in order to give priority to the reductionin power consumption, the main screen 2003 may be formed by a liquidcrystal display panel and the sub screen may be formed by an EL displaypanel so that the sub screen may be a structure capable on and off.According to the invention, a display device with high reliability canbe formed even when such a large size substrate is used and a largenumber of TFTs or electronic components are used.

FIG. 20(B) is a television device having a large display portion, forexample, with a size of 20 to 80 inches. The television device includesa housing 2010, a keyboard portion 2012 which is an operation portion, adisplay portion 2011, a speaker portion 2013 and the like. The inventionis applied to the manufacture of the display portion 2011. A flexiblesubstance is used for the display portion of FIG. 20(B), thereby thetelevision device has a curved display portion. The shape of the displayportion can be designed freely in this manner, therefore, a televisiondevice with a desired shape can be manufactured.

By the invention, the display device can be formed by a simple step,thereby cost can be reduced as well. Therefore, a television deviceusing the invention can be formed at low cost even with a large displayportion. Accordingly, a television device with high performance and highreliability can be manufactured with high yield.

It is needless to say that the invention is not limited to thetelevision device and can be applied to various applications as a largearea display medium such as a monitor of a personal computer, aninformation display board at a train station, airport and the like, anadvertisement display board on the streets.

Embodiment Mode 7

This embodiment mode of the invention is described with reference toFIGS. 25, 26, 33 and 34. This embodiment mode shows an example of anactive matrix type display device using the invention which has adifferent pixel arrangement and different position of spacers.Therefore, repetitive description on the same portion or a portionhaving a similar function is omitted.

FIG. 25 is a top plan view of a pixel region of stripe alignment inwhich pixels are arranged in stripes. A spacer 782 is formed over afirst electrode layer 780 which is a pixel electrode layer and a spacer781 is formed over an insulator (insulating layer) 783 which functionsas a partition covering an and portion of the first electrode layer 780.The spacer 781 is formed over the intersection of a gate line and asource line with the insulator 783 interposed therebetween. A mask issupported by the spacer 781 and the spacer 782 when forming anelectroluminescent layer, thereby damage of the first electrode layer isnot caused by the mask. A display defect due to a shape defect in thefirst electrode layer and the like are not generated, thereby a displaydevice with high image quality and high reliability can be manufactured.

Although an inorganic insulating material or an organic insulatingmaterial can be used for the spacers, in this embodiment mode, polyimideis used for the spacer 781 and the spacer 782, and the spacer 781 has aheight of 1 to 1.5 μm (in this embodiment mode, 1.5 μm), which has atapered bell shape of which a diameter is gradually increased toward thebottom surface from the top surface with a diameter of 10 to 15 μm (inthis embodiment mode, 15 μm) on the top plan view. The spacer 781 isprovided in a position between the power source line and the source lineand close to the pixel electrode layer, thereby a mask for forming anelectroluminescent layer can be supported fairly stable. Therefore, thepixel electrode layer can be protected from a contact with the mask.

FIG. 33 is a top plan view of a pixel region of stripe alignment inwhich a pixel is arranged in stripe. A spacer 582 is formed over a firstelectrode layer 580 which is a pixel electrode layer and a spacer 581 isformed over an insulator (insulating layer) 583 which functions as apartition covering an end portion of the first electrode layer 580. Amask when forming an electroluminescent layer is supported by the spacer581 and the spacer 582, thereby damage of the first electrode layer isnot caused by the mask.

Although an inorganic insulating material or an organic insulatingmaterial can be used for the spacers, in this embodiment mode, acrylicis used for the spacer 581 and the spacer 582, and the spacer 581 has aheight of 1 to 1.5 μm (in this embodiment mode, 1.5 μm), which has atapered bell shape of which a diameter is gradually increased toward thebottom surface from the top surface with a diameter of 5 μm on the topplan view. The spacer 781 is provided in a position between the powersource line and the source line and close to the pixel electrode layer,thereby a mask for forming an electroluminescent layer can be supportedfairly stable. Therefore, the pixel electrode layer can be protectedfrom a contact with the mask. A display defect due to a shape defect inthe first electrode layer and the like are not generated, thereby adisplay device with high image quality and high reliability can bemanufactured.

Shown are examples in which the spacers over the insulator covering theperiphery of the pixel electrode layer is provided along the gate linecorresponding to the intersection of the gate line and the source linein FIG. 25 and the spacer thereof is provided along the source line inFIG. 33. However, description is made on an example of a display devicehaving two kinds of spacers of a spacer 591 a provided along a gate lineand a spacer 591 b provided along a source line as shown in FIG. 34.

FIG. 34(A) is also a top plan view of a pixel region of stripe alignmentin which pixels are arranged in stripes similarly to FIGS. 25 and 33. Aspacer 592 is formed over a first electrode layer 590 which is a pixelelectrode layer, and the spacer 591 a and the spacer 591 b are formedover an insulator (insulating layer) 593 which functions as a partitioncovering an end portion of the first electrode layer 590. The spacer 591a is formed over the intersection of the gate line and the source linealong the gate line with the insulator 593 interposed therebetween.Further, the spacer 591 b is formed along the source line with theinsulator 593 interposed therebetween.

FIG. 34(B) shows a cross sectional diagram along line C-D of FIG. 34(A).A gate line 597 is formed over a substrate 595 and a gate insulatinglayer 596 is formed. The spacer 591 a and the spacer 591 b are providedover the insulator 593 which functions as a partition. In thisembodiment mode, each film thickness (height) of the spacer 591 a, thespacer 591 b, and the insulator 593 is 1.5 μm and total height of theinsulator 593 and the spacer 591 a or the spacer 591 b is 3 μm. A bottomsurface of the spacer 591 a has a diameter of 10 to 15 μm (in thisembodiment mode, 15 μm) and a bottom surface of the spacer 591 b has adiameter of 5 μm. Each shape of both the spacer 591 a and the spacer 591b has a tapered shape of which the diameter is gradually increased alonga thickness direction from the top surface to the bottom surface. Thespacer can be stable with an appropriate tapered shape, therefore, avapor deposition mask can also be supported stably. Further, as shown inFIG. 34(B), the spacer 591 b has a round shape and a smooth shape havingcurvatures. The spacer 591 b is provided in a position between the powersource line and the source line and close to the pixel electrode layer,thereby a mask for forming an electroluminescent layer can be supportedfairly stable.

In this manner, by providing two or more kinds of spacers with differentsize and shapes are provided, a mask for forming an electroluminescentlayer can be supported fairly stable. A mask is supported by the spacer592, the spacer 591 a, and the spacer 591 b for forming anelectroluminescent layer, thereby damage of the first electrode layer isnot caused by the mask. A display defect due to a shape defect in thefirst electrode layer and the like are not generated, thereby a displaydevice with high image quality and high reliability can be manufactured.

FIG. 26 is a top plan view of a pixel region with a delta arrangement inwhich pixels are shifted by a half pitch per one line. A spacer 792 isformed over a first electrode layer 790 which is a pixel electrodelayer, and a spacer 791 is formed over an insulator (insulating layer)793 which functions as a partition covering an end portion of the firstelectrode layer 790. Although the spacer 782 over the first electrodelayer 780 in FIG. 25 is formed without contacting with the insulator783, the spacer 792 over the first electrode layer 790 in FIG. 26 isformed in contact with the insulator. In this manner, a spacer shape canbe freely set. A mask is supported by the spacer 791 and the spacer 792when forming an electroluminescent layer, thereby damage of the firstelectrode layer is not caused by the mask. A display defect due to ashape defect in the first electrode layer and the like are notgenerated, thereby a display device with high image quality and highreliability can be manufactured.

Embodiment Mode 8

This embodiment mode of the invention is described with reference toFIG. 27. This embodiment mode shows an example of a passive matrix typedisplay device using the invention. Therefore, repetitive description onthe same portion or a portion having a similar function is omitted.

FIG. 27(A) is a top plan view of a passive type display device and FIG.27(B) is a cross sectional diagram along line A-B of FIG. 27(A). A firstelectrode layer 751 is formed over a substrate 750, and a spacer 752 andan insulator (insulating layer) 753 which functions as a partition areformed over the first electrode layer. A spacer 754 is formed over theinsulator 753 and an electroluminescent layer 755 and a second electrodelayer 756 are formed over the first electrode layer 751 to form a lightemitting element. A mask is supported by the spacer 752 and the spacer754 when the electroluminescent layer 755 is vapor-deposited. Therefore,damage of the first electrode layer is not caused by the mask. A displaydefect due to a shape defect in the first electrode layer and the likeare not generated, thereby a passive type display device with high imagequality and high reliability can be manufactured.

Embodiment Mode 9

This embodiment mode of the invention is described with reference toFIGS. 24 and 35. This embodiment mode shows an example in which achannel etched inverted stagger type thin film transistor is used for athin film transistor and a first interlayer insulating layer and asecond interlayer insulating layer are not formed in the display devicemanufactured in Embodiment Mode 1. Therefore, repetitive description onthe same portion or a portion having a similar function is omitted.

In a display device shown in FIG. 24, an inverted stagger type thin filmtransistor 701 and an inverted stagger type thin film transistor 702 areprovided in a peripheral driver circuit region 255; an inverted staggertype thin film transistor 703, a first conductive layer 704, a spacer705 a, a spacer 705 b, an insulator (insulating layer) 709, anelectroluminescent layer 707, a spacer 706, a second electrode layer708, a filling material 711, and a sealing substrate 710 are provided ina pixel region 256; a sealing material 712 is provided in a sealingregion, a terminal electrode layer 713, an anisotropic conductive layer714, an FPC 715, a polarizing plate 717, and a protective film 716 to bea passivation film me provided, which are provided over a substrate 700.

Each of a gate electrode layer, a source electrode layer and a drainelectrode layer of the inverted stagger type thin film transistor 701,the inverted stagger type thin film transistor 702, and the invertedstagger type thin film transistor 703 manufactured in this embodimentmode are formed by a droplet discharge method. The droplet dischargemethod is a method in which a composition having a liquid conductivematerial is discharged and solidified by drying and baking to form aconductive layer and an electrode layer. When a composition including aninsulating material is discharged and solidified by drying and baking,an insulating layer can also be formed. A component of a display devicesuch as a conductive layer and an insulating layer can be selectivelyformed so that steps are simplified and a material loss can beprevented. Therefore, a display device can be manufactured at low costwith high productivity.

A droplet discharge means used for the droplet discharge method is ageneric name of a means for discharging droplets such as a nozzle havinga discharge orifice of composition, or a head provided with one or aplurality of nozzles. A diameter of a nozzle of a droplet dischargemeans is set to 0.02 to 100 μm (preferably 30 μm or smaller) and adischarged amount of composition discharged from the nozzle is set to0.001 to 100 pl (preferably 0.1 to 40 pl, and more preferably 10 pl orless). The discharged amount increases in proportion to the diameter ofthe nozzle. Further, a distance between a processing object and thedischarge orifice of the nozzle is preferably as close as possible fordischarging onto a desired position and preferably set to about 0.1 to 3mm (preferably 1 mm or less).

As the composition discharged from the discharge orifice, a compositionin which a conductive material is dissolved or dispersed in a solvent isused. The conductive material corresponds to fine particles ordispersive nanoparticles of metal such as Ag, Au, Cu, Ni, Pt, Pd, Ir,Rh, W, and Al, metal sulfide of Cd and Zn, oxide of Fe, Ti, Si, Ge, Si,Zr, Ba, and the like, and silver halide. Moreover, the conductivematerial corresponds to indium tin oxide (ITO), ITSO composed of indiumtin oxide and silicon oxide, organic indium, organotin, zinc oxide,titanium nitride, or the like which is used as a transparent conductivefilm. However, as the composition discharged from the discharge orifice,a composition in which any one of gold, silver, and copper is dissolvedor dispersed in a solvent is preferably used in consideration of aspecific resistance value, and more preferably, silver and copper havinglow resistance may be used. However, in case of using silver or copper,a barrier film is also preferably provided as a measure against animpurity. As a barrier film, a silicon nitride film or nickel boron(NiB) can be used.

In addition, a particle in which the periphery of a conductive materialis coated with other conductive materials in a plurality of layers maybe used as well. For example, a three-layer structure particle may beused in which the periphery of copper is coated with nickel boron (NiB),and then the periphery thereof is coated with silver and the like. Asfor solvents, esters such as butyl acetate and ethyl acetate, alcoholssuch as isopropyl alcohol and ethyl alcohol, organic solvents such asmethyl ethyl ketone and acetone, and water, or the like are used. Theviscosity of the composition is preferably 20 mPa·s (cp) or less. Thisis because the composition is prevented from drying or the compositioncan be smoothly discharged from the discharge orifice. Moreover, thesurface tension of the composition is preferably 40 mN/m or less.However, the viscosity of the composition and the like may beappropriately adjusted in accordance with a solvent to be used andapplications. As one example, the viscosity of a composition in whichITO, organic indium, or organotin is dissolved or dispersed in a solventmay be set to 5 to 20 mPa·s, the viscosity of a composition in whichsilver is dissolved or dispersed in a solvent may be set to 5 to 20mPa·s, and the viscosity of a composition in which gold is dissolved ordispersed in a solvent may be set to 5 to 20 mPa·s.

Further, a plurality of conductive materials may be stacked as theconductive layer. In addition, after forming a conductive layer by adroplet discharge method using silver as a conductive material, it maybe plated with copper or the like. Plating may be performed byelectroplating or a chemical (electroless) plating method. Plating maybe performed by soaking a substrate surface into a container filled witha solution having a plating material. A solution having a platingmaterial may be applied to flow over the substrate surface with thesubstrate placed obliquely (or vertically). When the plating isperformed by applying a solution with the substrate stand, there is anadvantage of downsizing a step apparatus.

The diameter of a conductive particle is preferably as small as possiblefor preventing clogged nozzles and manufacturing a high-definitionpattern although it depends on the diameter of each nozzle, a desiredshape of a pattern, and the like. Preferably, the diameter of theparticle is preferably 0.1 μm or smaller. The composition is formed by aknown method such as an electrolytic method, an atomizing method, a wetreducing method, and the particle size thereof is generally about 0.01to 10 μm. However, when formed by a gas evaporation method, ananomolecule protected with a dispersant is as minute as about 7 nm.Moreover, when each surface of particles is covered using a coatingagent, the nanoparticle does not cohere in the solvent and is stablydispersed in the solvent at a room temperature to show almost the samebehavior as that of liquid. Accordingly, a coating agent is preferablyused.

Moreover, the step of discharging the composition may be performed underlow pressure. The step of discharging the composition is preferablyperformed under low pressure since an oxide film and the like are notformed on the surfaces of the conductive layers. After discharging thecomposition, one or both of a drying step and a baking step is/areperformed. Both of the drying step and the baking step are heattreatment steps. For example, the drying is performed at 100° C. for 3minutes whereas the baking is performed at 200 to 350° C. for 15 to 60minutes, and the purposes, temperatures, and time thereof vary. Thedrying step and the baking step are performed under normal pressure orunder low pressure by laser light irradiation, rapid thermal annealing,an annealing furnace, and the like. Note that the timing of performingthe heat treatment and the number of the heat treatment are notparticularly limited. The substrate may be heated in advance so as toperform the drying and baking steps favorably. At this time, althoughthe temperature depends on a material of the substrate and the like, itis generally set to be 100 to 800° C. (preferably, 200 to 350° C.).According to this step, a resin on the periphery is cured and shrunk sothat the nanoparticles are in contact with one another and fusing andwelding are accelerated as well as volatilizing the solvent in thecomposition or removing the dispersant chemically.

A gas laser or a solid state laser of a continuous wave oscillation or apulsed oscillation may be used for laser light irradiation which is usedin the drying or baking step. An excimer laser, a He—Cd laser, an Arlaser and the like are cited as the former gas laser, while lasers usingcrystals such as YAG, YVO₄ and GdVO₄ doped with Cr, Nd and the like arecited as the latter solid state laser. Note that it is preferable to usethe continuous wave laser in relation to the rate of absorption of laserlight. Alternatively, a so-called hybrid laser irradiation methodcombining a pulsed oscillation and a continuous wave oscillation may beused. Note that the heat treatment with laser light irradiation may beinstantaneously performed for several microseconds to several tenseconds so as not to destroy the substrate 700 depending on a heatresistant property of the substrate 700. Rapid thermal annealing (RTA)is performed by instantaneously heating the substrate for severalminutes to several microseconds while rapidly raising the temperatureusing an infrared lamp, a halogen lamp, and the like which emitultraviolet light through infrared light under an inert gas atmosphere.This treatment is performed instantaneously, therefore, only a thin filmof an outmost surface can be substantially heated so that underlyingfilms are not affected. That is, a substrate having a low heatresistance property such as a plastic substrate is not affected either.

Further, after forming the conductive layer, the surface thereof may bepressed by pressure to be planarized for increasing the planarity. Asthe method for pressing, a roller-shaped object may scan the surface toreduce and level the depression/projection, or the surface may bepressed vertically with a flat plate. In pressing a heating step may beperformed. Moreover, the surface may be softened or welded using asolvent or the like and the depression/projection portion of the surfacemay be removed with an air knife. Alternatively, thedepression/projection may be polished using a CMP method. In the casewhere a depression/projection occurs due to the droplet dischargemethod, this step can be applied to the case of planarizing the surface.

In this embodiment mode, an amorphous semiconductor is used as asemiconductor layer and a semiconductor layer having one conductive typemay be formed if necessity. In this embodiment mode, a semiconductorlayer and an amorphous N-type semiconductor layer as a semiconductorlayer with a semiconductor layer having one conductive type are stacked.Further, by forming an N-type semiconductor layer an NMOS structure ofan N-channel TFT, a PMOS structure of a P-channel TFT in which a P-typesemiconductor layer is formed, and a CMOS structure of an N-channel TFTand a P-channel TFT can be manufactured. In this embodiment mode, theinverted stagger type thin film transistor 701 and the inverted staggertype thin film transistor 703 are formed with N-channel TFTs, and theinverted stagger type thin film transistor 702 is formed with aP-channel TFT, thereby the inverted stagger type thin film transistor701 and the inverted stagger type thin film transistor 702 form a CMOSstructure in the peripheral driver circuit region 255.

Moreover, by adding an element imparting conductivity by doping and byforming an impurity region in the semiconductor layer to impartconductivity, an N-channel TFT and a P-channel TFT can also be formed.Instead of forming an N-type semiconductor layer, conductivity may beimparted to the semiconductor layer by performing plasma treatment withPH₃ gas.

Further, a semiconductor layer may be formed using an organicsemiconductor material as a semiconductor by a printing method, a spraymethod, a spin coating method, a droplet discharge method, or the like.In this case, the aforementioned etching step is not required,therefore, the number of steps can be reduced. As an organicsemiconductor, a low molecular weight material, a high molecular weightmaterial, and the like can be used, and a material such as an organicpigment and a conductive high molecular weight material can be used aswell. As the organic semiconductor material used in the invention, ahigh molecular weight material of π electron conjugated system of whicha skeleton is composed of conjugated double bonds is preferable.Typically, a soluble high molecular weight material such aspolythiophene, polyfluorene, poly(3-alkylthiophene), polythiophenederivative and pentacene can be used.

A mask for forming an electroluminescent layer is supported by thespacer 705 a, the spacer 705 b, and the spacer 706, thereby damage ofthe pixel electrode layer is not caused by the mask. Therefore, adisplay device with high image quality and high reliability can bemanufactured.

A structure described in the aforementioned embodiment modes can be usedfor a structure of a light emitting element applicable to the invention.Further, a structure of a light emitting element in the followingembodiment mode can also be used in combination with the aforementionedembodiment modes. A light emitting element has a plurality of layersinterposed between a pair of electrodes, and at least one layer thereofis composed of a layer containing a light emitting substance (alsoreferred to as an electroluminescent layer).

An example of a favorable light emitting element has a layer containinga light emitting substance and a mixed region which includes at leastone layer among other layers containing an inorganic substance and anorganic substance. This mixed layer can be a hole injecting/transportinglayer or an electron injecting/transporting layer by selecting aninorganic substance or an organic substance.

An example of a combination of hole injecting/transporting layers is asfollows. As an inorganic substance, there are molybdenum oxide(MoO_(x)), vanadium oxide (VO_(x)), ruthenium oxide (RuO_(x)), tungstenoxide (WO_(x)), and the like. Besides, indium tin oxide (ITO), zincoxide (ZnO), or tin oxide (SnO) can be used. However, the invention isnot limited to the substances described here and other substances may beused as well. As an organic substance, a compound having high holetransporting property can be used such as an aromatic amine (that is,the one having a benzene ring-nitrogen bond) compound, for example,4,4′-bis[N-(1-naphthyl)-N-phenyl-amino]-biphenyl (abbreviated: α-NPD),4,4′-bias[N-(3-methylphenyl)-N-phenyl-amino]-biphenyl (abbreviated:TPD), 4,4′,4″-tris(N,N-diphenyl-amino)-triphenylamine (abbreviated:TDATA), 4,4′,4″-tris[N-(3-methylphenyl)-N-phenyl-amino]-triphenylamine(abbreviated: MTDATA), and the like. However, other than the substancesdescribed here, and other substances may be used as well.

An example of a combination of electron injecting/transporting layers isas follows. As an inorganic substance, there are any one or more metalsshowing an electron donor property selected from lithium, cesium,magnesium, calcium, barium, erbium, and ytterbium. As an organicsubstance, a substance having a high electron transporting property isused such as a layer formed of a metal complex having a quinolineskeleton or a benzoquinoline skeleton such astris(8-quinolinolato)aluminum (abbreviated: Alq₃),tris(5-methyl-8-quinolinolato)aluminum (abbreviated: Almq₃),bis(10-hydroxybenzo[h]-quinolinato)beryllium (abbreviated: BeBq₂), andbis(2-methyl-8-quinolinolato)-4-phenylphenolate-aluminum (abbreviated:BAlq). Besides, a metal complex containing oxazole-based orthiazole-based ligand such as bis[2-(2-hydroxyphenyl)benzoxazolato]zinc(abbreviated: Zn(BOX)₂) and bis[2-(2-hydroxyphenyl)-benzothiazolato]zinc(abbreviated: Zn(BTZ)₂) and the like can also be used. Furthermore,other than the metal complex,2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviated:PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazole-2-yl]benzene(abbreviated: OXD-7),3-(4-tert-butylphenyl)-4-phenyl-5-(4-biphenylyl)-1,2,4-triazole(abbreviated: TAZ),3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenylyl)-1,2,4-triazole(abbreviated: p-EtTAZ), bathophenanthroline (abbreviated: BPhen),bathocuproin (abbreviated: BCP), and the like can be used as well.However, other than the substances described in this embodiment mode,and the substances described in the aforementioned embodiment modes andother substances may be used as well.

A light emitting element is formed by appropriately combining a layercontaining a light emitting substance and the aforementioned mixedlayer. For example, such a structure can be employed that a holeinjecting/transporting layer or an electron injecting/transporting layeris arranged on one side of the layer containing a light emittingsubstance. Further, such a structure can be employed that a holeinjecting/transporting layer is arranged on one side while an electroninjecting/transporting layer is arranged on the other side with thelayer containing a light emitting substance interposed therebetween.

At least one of or both of electrodes between the pair of electrodesis/are formed of indium oxide, tin oxide, zinc oxide, or a transparentconductive substance in which at least a plurality of the aforementionedoxide are mixed. For example, there are a mixture of indium oxide andtin oxide (also referred to as ITO), a mixture of indium oxide, indiumoxide and zinc oxide and the like. Further, a transparent conductivesubstance containing an appropriate amount of oxide such as siliconoxide, titanium oxide, molybdenumn oxide for controlling crystallizationof these oxides and maintaining the smoothness of the surface may be aswell. Further, at least one electrode between the pair of electrodes maybe formed of a metal substance containing as a main component aluminum,silver, titanium, tantalum, molybdenum, chromium, tungsten and the like.

The display device in FIG. 24 is a top emission type display device inwhich light is extracted from the sealing substrate 710 side, and thescaling substrate 710 has a polarizing plate 716 and a protective film716 on the element substrate side. The polarizing plate 716 is coveredwith the sealing substrate 710 and the protective film 716 to beprotected from contamination, damage and the like. Further, aretardation plate (λ/4 plate and λ/2 plate) or an anti-reflection filmmay be provided as well as the polarizing plate. When using theretardation plate and the polarizing plate, reflection light of externalincident light can be blocked, thereby a higher resolution and finerimage can be displayed.

FIG. 35 shows a dual emission type display device having a polarizingplate and a protective film. The display device in FIG. 35 correspondsto a dual emission type of the display device in FIG. 24, and the samereference numeral is used in common for the same portion or a portionhaving a similar function as that in a different drawing of FIG. 24 andthe repetitive description thereof is omitted. In FIG. 35, a protectivefilm is provided over a sealing substrate as a protective film 726 onthe opposite side to an element substrate. Moreover, in the displaydevice in FIG. 35, light is emitted from the sealing substrate 710 sideand the element substrate 700 side as shown by arrows. Therefore, apolarizing plate 728 and a protective film 729 are provided on a sidehaving an element of the element substrate 700 and the opposite sidethereto. The protective film 726 and the protective film 729 protect thedisplay device and the polarizing plate from contamination, damage, andthe like to improve the reliability of the display device. Further, aretardation plate (λ/4 plate and λ/2 plate) or an anti-reflection filmmay be provided as well as the polarizing plate. When using theretardation plate and the polarizing plate, reflection light of externalincident light can be blocked, thereby a higher resolution and finerimage can be displayed.

The protective film 716 can be formed of a material selected fromsilicon oxide, silicon nitride, silicon oxynitride, silicon nitrideoxide, aluminum nitride (AlN), aluminum oxynitride (AlON), aluminumnitride oxide (AlNO) in which nitrogen content is more than oxygencontent, aluminum oxide, diamond-like carbon (DLC), anitrogen-containing carbon film (CN) and other substances containing aninorganic insulating material. Further, a siloxane resin may be used aswell. Moreover, an organic insulating material may be used as well, andas an organic material, polyimide, acrylic, polyamide, polyimide amide,resist, benzocyclobutene, or polysilazane can be used. A coated filmwith high planarity by a coating method may be used as well. Further, aconductive material may also be used in the case of a design by which adefect of electrical characteristics such as a short-circuit does notoccur. In the display devices in FIGS. 24 and 35, aluminum nitride oxide(AlN_(X)O_(Y)) is used as the protective film 716, the protective film726, and the protective film 729, and the proportion of O in thecomposition of AlN_(X)O_(Y) is 0.1 to 30 atomic %. Since an AlN_(X)O_(Y)film has a heat diffusion effect which diffuses heat, heat generatedfrom a light emitting element can be diffused, and thereby thedeterioration of the light emitting element and display device can beprevented to improve the reliability. As in FIG. 24, when the protectivefilm 716 is provided on the light emitting element side, the protectivefilm 716 is closer to the light emitting element, thereby the heatdiffusion effect can be largely achieved.

In this embodiment mode, a liquid drying material is injected bydropping and solidified to be used as the filling material 711.Therefore, the substance has a moisture absorbing property, thereby amoisture absorbing effect can be obtained to prevent deterioration ofthe element. Further, as in this embodiment mode, when a projectionportion is formed by the spacer 198 to obtain a structure in which thesealing substrate 195 is supported by the projection portion, a spacebetween the element substrate and the sealing substrate can becontrolled to be uniform. When the space is uniform, the space can befilled with the filling material 71 uniformly. Therefore, a displaydefect such that light emitted from a light emitting element isinterfered and the like are not generated so that good and high imagequality display can be performed.

Embodiment Mode 10

This embodiment mode is described with reference to FIG. 21. Thisembodiment mode shows an example of a module using a panel having thedisplay device manufactured in Embodiment Modes 1 to 9.

In an information terminal module shown in FIG. 21(A), a controller 901,a central processing unit (CPU) 902, a memory 911, a power sourcecircuit 903, an audio processing circuit 929, a transmission/receptioncircuit 904, and other elements such as a resistor, a buffer, and acapacitor are mounted onto a printed wiring board 946. Further, a panel900 is connected to the printed wiring board 946 through a flexiblewiring board (FPC) 908.

The panel 900 is provided with a pixel portion 905 in which a lightemitting element is provided in each pixel, a first scan line drivercircuit 906 a and a second scan line driver circuit 906 b which selectthe pixel included in the pixel portion 905, and a signal line drivercircuit 907 which supplies a video signal to the selected pixel.

Various control signals are inputted and outputted through an interface(I/F) portion 909 provided over the printed wiring board 946. Further,an antenna port 910 for transmitting and receiving signals to an antennais provided over the printed wiring board 946.

Note that the printed wiring board 946 is connected to the panel 900through the FPC 908 in this embodiment mode, however, the invention isnot necessarily limited to this structure. The controller 901, the audioprocessing circuit 929, the memory 911, the CPU 902 or the power sourcecircuit 903 may be directly mounted onto the panel 900 using the COG(Chip on Glass) method. Further, various elements such as a capacitorand a buffer are provided over the printed wiring board 946, thereby itcan be prevented that a noise occurs in the power source voltage andsignals and the dull rise of the signal is prevented.

FIG. 21(B) shows a block diagram of the module shown in FIG. 21(A). Thismodule 999 includes a VRAM 932, a DRAM 925, a flash memory 926 and thelike as the memory 911. Image data displayed on the panel is stored inthe VRAM 932, image data or audio data is stored in the DRAM 925, andvarious programs are stored in the flash memory.

The power source circuit 903 generates a power source voltage applied tothe panel 900, the controller 901, the CPU 902, the audio processingcircuit 929, the memory 911, and the transmission/reception circuit 931.Moreover, there is a case where a current source is provided in thepower source circuit 903 depending on the specification of the panel.

The CPU 902 has a control signal generating circuit 920, a decoder 921,a register 922, an arithmetic circuit 923, a RAM 924, an interface 935for the CPU and the like. Various signals inputted to the CPU 902through the interface 935 are once held in the register 922 and theninputted to the arithmetic circuit 923, the decoder 921 and the like. Inthe arithmetic circuit 923, an arithmetic operation is performed basedon the inputted signals to specify the address of various instructions.Meanwhile, the signals inputted to the decoder 921 are decoded andinputted to the control signal generating circuit 920. The controlsignal generating circuit 920 generates signals containing variousinstructions based on the inputted signals, and then transmits thesignals to the address specified by the arithmetic circuit 923,specifically the memory 911, the transmission/reception circuit 931, theaudio processing circuit 929, the controller 901 and the like.

Each of the memory 911, the transmission/reception circuit 931, theaudio processing circuit 929, and the controller 901 operates inaccordance with the received instruction. The operation thereof isbriefly described as follows.

Signals inputted from an input means 934 are transmitted to the CPU 902which is mounted onto the printed wiring board 946 through the interface909. The control signal generating circuit 920 converts the image datastored in the VRAM 932 into a predetermined format in accordance withthe signals transmitted from the input means 934 such as a pointingdevice and a keyboard, and transmits it to the controller 901.

The controller 901 conducts data processing on the signals containingimage data transmitted from the CPU 902 in accordance with thespecification of the panel, and supplies it to the panel 900. Further,the controller 901 generates an Hsync signal, a Vsync signal, a clocksignal CLK, an alternating current voltage (AC Cont), and a switchingsignal L/R based on the power source voltage inputted from the powersource voltage 903 and the various signals inputted from the CPU 902,and supplies them to the panel 900.

Signals transmitted and received as electromagnetic waves are processedby an antenna 933 in the transmission/reception circuit 904.Specifically, included is a high frequency circuit such as an isolator,a band pass filter, a VCO (Voltage Controlled Oscillator), an LPF (LowPass Filter), a coupler, and a balun. Signals containing audio dataamong the signals transmitted and received by the transmission/receptioncircuit 904 are transmitted to the audio processing circuit 929 inaccordance with the instruction of the CPU 902.

The signals containing audio data transmitted in accordance with theinstruction of the CPU 902 are demodulated into audio signals by theaudio processing circuit 929 to be transmitted to a speaker 928.Further, audio signals transmitted from a microphone 927 are modulatedby the audio processing circuit 929 to be transmitted to thetransmission/reception circuit 904 in accordance with the instruction ofthe CPU 902.

The controller 901, the CPU 902, the power source circuit 903, the audioprocessing circuit 929, and the memory 911 can be mounted as a packageof this embodiment mode. This embodiment mode can be applied to anycircuits but a high frequency circuit such as an isolator, a bend passfilter, a VCO (Voltage Controlled Oscillator), an LPF (Low Pass Filter),a coupler, and a balun.

The display panel 900 is provided with a spacer over a pixel electrodeor over an insulator covering the periphery of the pixel electrode.Accordingly, a module provided with this display panel 900 supports amask used for forming an electroluminescent layer so that the mask doesnot contact the pixel electrode, therefore, damage of the pixelelectrode can be prevented, thereby an effect of high image qualitydisplay and high reliability can be obtained.

Embodiment Mode 11

This embodiment mode is described with reference to FIGS. 21 and 22.FIG. 22 shows one mode of a portable compact phone device (portablephone) using wireless including the module manufactured in accordancewith Embodiment Mode 10. The display panel 900 can be detachablyincorporated in a housing 1001 and so that it can easily be integratedwith the module 999. The shape and size of the housing 1001 can beappropriately changed in accordance with an incorporated electronicapparatus.

The housing 1001 to which the display panel 900 is fixed is fitted intothe printed wiring board 946 to be completed as a module. A controller,a CPU, a memory, a power source circuit, and other elements such as aresistor, a buffer, and a capacitor are mounted onto the printed wiringboard 946. Furthermore, an audio processing circuit including amicrophone 995 and a speaker 995, and a signal processing circuit 993such as a transmission/reception circuit are provided. The panel 900 isconnected to the printed wiring board 946 through the FPC 908.

Such a module 999, an input means 998, and a battery 997 are put insidea housing 996. A pixel portion of the display panel 900 is arranged tobe visible from an opening window formed in the housing 996.

The display panel 900 is provided with a spacer over a pixel electrodeor over an insulator covering the periphery of the pixel electrode.Accordingly, a module provided with this display panel 900 supports amask used for forming an electroluminescent layer so that the mask doesnot contact the pixel electrode, therefore, damage of the pixelelectrode can be prevented, thereby an effect of high image qualitydisplay and high reliability can be obtained.

The housing 996 shown in FIG. 22 shows an example of an externalappearance of a phone device. However, an electronic apparatus inaccordance with this embodiment mode may be changed into various modesin accordance with the function and application. An example of the modesis described in the following embodiment mode.

Embodiment Mode 12

By applying the invention, various display devices can be manufactured.That is, the invention can be applied to various electronic apparatusesin which these display devices are incorporated in a display portionthereof.

As examples of such electronic apparatuses, there are a camera such as avideo camera and a digital camera, a projector, a head mounted display(a goggle type display), a car navigation, a car stereo, a personalcomputer, a game machine, a portable information terminal (a mobilecomputer, a portable phone, an electronic book or the like), an imagereproducing device provided with a recording medium (specifically, adevice which reproduces a recording medium such as a Digital VersatileDisc (DVD) and has a display which can display the image) and the like.Examples of these are shown in FIG. 23.

FIG. 23(A) is a computer including a main body 2101, a housing 2102, adisplay portion 2103, a keyboard 2104, an external connecting port 2105,a pointing mouse 2106 and the like. When using the invention, a computerwhich displays a high quality image with high reliability can becompleted even when the computer is downsized and pixels become finer.

FIG. 23(B) is an image reproducing device provided with a recordingmedium (specifically a DVD reproducing device) including a main body2201, a housing 2202, a display portion A 2203, a display portion B2204, a recording medium (such as a DVD) reading portion 2205, anoperating key 2206, a speaker portion 2207 and the like. The displayportion A 2203 mainly displays image data while the display portion B2204 mainly displays text data. When using the invention, an imagereproducing device which displays a high quality image with highreliability can be completed even when the image reproducing device isdownsized and pixels become finer.

FIG. 23(C) is a portable phone including a main body 2301, an audiooutput portion 2302, an audio input portion 2303, a display portion2304, operating switches 2305, an antenna 2306 and the like. When usingthe invention, a portable phone which displays a high quality image withhigh reliability can be completed even when the portable phone isdownsized and pixels become finer.

FIG. 23(D) is a video camera including a main body 2401, a displayportion 2402, a housing 2403, an external connecting port 2404, a remotecontrol receiving portion 2405, an image receiving portion 2406, abattery 2407, an audio input portion 2408, an eyepiece portion 2409,operating keys 2410 and the like. When using the invention, a videocamera which displays a high quality image with high reliability can becompleted even when the video camera is downsized and pixels becomefiner. This embodiment mode can be freely combined with theaforementioned embodiment modes.

What is claimed is:
 1. A semiconductor device comprising: a transistorcomprising a semiconductor layer over a first substrate; a firstinsulating layer over the semiconductor layer, the first insulatinglayer comprising silicon; a second insulating layer over the firstinsulating layer, the second insulating layer comprising a first organicmaterial; a first electrode over the second insulating layer; a thirdinsulating layer covering an end portion of the first electrode, thethird insulating layer comprising a second organic material; a layercomprising an organic compound over the first electrode and the thirdinsulating layer; a second electrode over the layer; and a fourthinsulating layer over the second electrode, wherein the first electrodeis electrically connected to the transistor, wherein the thirdinsulating layer covers an end portion of the second insulating layer,wherein the fourth insulating layer covers the end portion of the secondinsulating layer and an end portion of the third insulating layer, andwherein the second insulating layer and the third insulating layer arein direct contact with the first insulating layer.
 2. The semiconductordevice according to claim 1, wherein the fourth insulating layercomprises aluminum and oxygen.
 3. The semiconductor device according toclaim 1, wherein the third insulating layer is adjacent to a convexportion, and wherein the convex portion comprises the second organicmaterial.
 4. The semiconductor device according to claim 1, furthercomprising a second substrate over the fourth insulating layer.
 5. Thesemiconductor device according to claim 1, wherein the first substrateis a flexible substrate.
 6. The semiconductor device according to claim1, wherein the layer is capable of emitting white light.
 7. Thesemiconductor device according to claim 1, wherein the first organicmaterial comprises any one of polyimide, acrylic, polyamide, andpolyimide amide.
 8. The semiconductor device according to claim 1,wherein the first organic material is the same as the second organicmaterial.
 9. A display module comprising the semiconductor deviceaccording to claim
 1. 10. An electronic apparatus comprising: a housing;and a display portion in the housing, wherein the display portioncomprises the display module according to claim
 9. 11. A semiconductordevice comprising: a transistor comprising a semiconductor layer over afirst substrate; a first insulating layer over the semiconductor layer,the first insulating layer comprising silicon; a second insulating layerover the first insulating layer, the second insulating layer comprisinga first organic material; a first electrode over the second insulatinglayer; a third insulating layer covering an end portion of the firstelectrode, the third insulating layer comprising a second organicmaterial; a first layer comprising a first organic compound over thefirst electrode and the third insulating layer; a second layercomprising a second organic compound over the third insulating layer; athird layer comprising a third organic compound over the thirdinsulating layer; a second electrode over the first layer, the secondlayer, and the third layer; and a fourth insulating layer over thesecond electrode, wherein the first organic compound, the second organiccompound, and the third organic compound are different from one another,wherein the first electrode is electrically connected to the transistor,wherein the third insulating layer covers an end portion of the secondinsulating layer, wherein the fourth insulating layer covers the endportion of the second insulating layer and an end portion of the thirdinsulating layer, and wherein the second insulating layer and the thirdinsulating layer are in direct contact with the first insulating layer.12. The semiconductor device according to claim 11, wherein the fourthinsulating layer comprises aluminum and oxygen.
 13. The semiconductordevice according to claim 11, wherein the third insulating layer isadjacent to a convex portion, and wherein the convex portion comprisesthe second organic material.
 14. The semiconductor device according toclaim 11, further comprising a second substrate over the fourthinsulating layer.
 15. The semiconductor device according to claim 11,wherein the first substrate is a flexible substrate.
 16. Thesemiconductor device according to claim 11, wherein the first layer iscapable of emitting white light.
 17. The semiconductor device accordingto claim 11, wherein the first organic material comprises any one ofpolyimide, acrylic, polyamide, and polyimide amide.
 18. Thesemiconductor device according to claim 11, wherein the first organicmaterial is the same as the second organic material.
 19. A displaymodule comprising the semiconductor device according to claim
 11. 20. Anelectronic apparatus comprising: a housing; and a display portion in thehousing, wherein the display portion comprises the display moduleaccording to claim 19.